draft-ietf-cellar-ebml-05.txt   draft-ietf-cellar-ebml-06.txt 
cellar S. Lhomme cellar S. Lhomme
Internet-Draft Internet-Draft
Intended status: Standards Track D. Rice Intended status: Standards Track D. Rice
Expires: January 19, 2019 Expires: March 1, 2019
M. Bunkus M. Bunkus
July 18, 2018 August 28, 2018
Extensible Binary Meta Language Extensible Binary Meta Language
draft-ietf-cellar-ebml-05 draft-ietf-cellar-ebml-06
Abstract Abstract
This document defines the Extensible Binary Meta Language (EBML) This document defines the Extensible Binary Meta Language (EBML)
format as a generalized file format for any type of data in a format as a generalized file format for any type of data in a
hierarchical form. EBML is designed as a binary equivalent to XML hierarchical form. EBML is designed as a binary equivalent to XML
and uses a storage-efficient approach to build nested Elements with and uses a storage-efficient approach to build nested Elements with
identifiers, lengths, and values. Similar to how an XML Schema identifiers, lengths, and values. Similar to how an XML Schema
defines the structure and semantics of an XML Document, this document defines the structure and semantics of an XML Document, this document
defines how EBML Schemas are created to convey the semantics of an defines how EBML Schemas are created to convey the semantics of an
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 19, 2019. This Internet-Draft will expire on March 1, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notation and Conventions . . . . . . . . . . . . . . . . . . 4 2. Notation and Conventions . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6 3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4. Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Variable Size Integer . . . . . . . . . . . . . . . . . . . . 7
6. Variable Size Integer . . . . . . . . . . . . . . . . . . . . 7 5.1. VINT_WIDTH . . . . . . . . . . . . . . . . . . . . . . . 8
6.1. VINT_WIDTH . . . . . . . . . . . . . . . . . . . . . . . 8 5.2. VINT_MARKER . . . . . . . . . . . . . . . . . . . . . . . 8
6.2. VINT_MARKER . . . . . . . . . . . . . . . . . . . . . . . 8 5.3. VINT_DATA . . . . . . . . . . . . . . . . . . . . . . . . 8
6.3. VINT_DATA . . . . . . . . . . . . . . . . . . . . . . . . 8 5.4. VINT Examples . . . . . . . . . . . . . . . . . . . . . . 9
6.4. VINT Examples . . . . . . . . . . . . . . . . . . . . . . 9 6. Element ID . . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Element ID . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. Element Data Size . . . . . . . . . . . . . . . . . . . . . . 11
8. Element Data Size . . . . . . . . . . . . . . . . . . . . . . 11 8. EBML Element Types . . . . . . . . . . . . . . . . . . . . . 12
9. EBML Element Types . . . . . . . . . . . . . . . . . . . . . 12 8.1. Signed Integer Element . . . . . . . . . . . . . . . . . 13
9.1. Signed Integer Element . . . . . . . . . . . . . . . . . 13 8.2. Unsigned Integer Element . . . . . . . . . . . . . . . . 13
9.2. Unsigned Integer Element . . . . . . . . . . . . . . . . 13 8.3. Float Element . . . . . . . . . . . . . . . . . . . . . . 13
9.3. Float Element . . . . . . . . . . . . . . . . . . . . . . 13 8.4. String Element . . . . . . . . . . . . . . . . . . . . . 14
9.4. String Element . . . . . . . . . . . . . . . . . . . . . 14 8.5. UTF-8 Element . . . . . . . . . . . . . . . . . . . . . . 14
9.5. UTF-8 Element . . . . . . . . . . . . . . . . . . . . . . 14 8.6. Date Element . . . . . . . . . . . . . . . . . . . . . . 14
9.6. Date Element . . . . . . . . . . . . . . . . . . . . . . 14 8.7. Master Element . . . . . . . . . . . . . . . . . . . . . 14
9.7. Master Element . . . . . . . . . . . . . . . . . . . . . 14 8.8. Binary Element . . . . . . . . . . . . . . . . . . . . . 15
9.8. Binary Element . . . . . . . . . . . . . . . . . . . . . 15 9. Terminating Elements . . . . . . . . . . . . . . . . . . . . 15
10. Terminating Elements . . . . . . . . . . . . . . . . . . . . 15 10. Guidelines for Updating Elements . . . . . . . . . . . . . . 16
11. Guidelines for Updating Elements . . . . . . . . . . . . . . 16 10.1. Reducing a Element Data in Size . . . . . . . . . . . . 16
11.1. Reducing a Element Data in Size . . . . . . . . . . . . 16 10.1.1. Adding a Void Element . . . . . . . . . . . . . . . 16
11.1.1. Adding a Void Element . . . . . . . . . . . . . . . 16 10.1.2. Extending the Element Data Size . . . . . . . . . . 16
11.1.2. Extending the Element Data Size . . . . . . . . . . 16 10.1.3. Terminating Element Data . . . . . . . . . . . . . . 17
11.1.3. Terminating Element Data . . . . . . . . . . . . . . 17 10.2. Considerations when Updating Elements with CRC . . . . . 17
11.2. Considerations when Updating Elements with CRC . . . . . 17 11. EBML Document . . . . . . . . . . . . . . . . . . . . . . . . 18
12. EBML Document . . . . . . . . . . . . . . . . . . . . . . . . 18 11.1. EBML Header . . . . . . . . . . . . . . . . . . . . . . 18
12.1. EBML Header . . . . . . . . . . . . . . . . . . . . . . 18 11.2. EBML Body . . . . . . . . . . . . . . . . . . . . . . . 18
12.2. EBML Body . . . . . . . . . . . . . . . . . . . . . . . 18 12. EBML Stream . . . . . . . . . . . . . . . . . . . . . . . . . 19
13. EBML Stream . . . . . . . . . . . . . . . . . . . . . . . . . 19 13. Elements semantic . . . . . . . . . . . . . . . . . . . . . . 19
14. Elements semantic . . . . . . . . . . . . . . . . . . . . . . 19 13.1. EBML Schema . . . . . . . . . . . . . . . . . . . . . . 19
14.1. EBML Schema . . . . . . . . . . . . . . . . . . . . . . 19 13.1.1. Element . . . . . . . . . . . . . . . . . . . . . . 20
14.1.1. Element . . . . . . . . . . . . . . . . . . . . . . 20 13.1.2. Attributes . . . . . . . . . . . . . . . . . . . . . 20
14.1.2. Attributes . . . . . . . . . . . . . . . . . . . . . 20 13.1.3. Element . . . . . . . . . . . . . . . . . . . . . . 20
14.1.3. Element . . . . . . . . . . . . . . . . . . . . . . 20 13.1.4. Attributes . . . . . . . . . . . . . . . . . . . . . 21
14.1.4. Attributes . . . . . . . . . . . . . . . . . . . . . 21 13.1.5. Element . . . . . . . . . . . . . . . . . . . . . . 26
14.1.5. Element . . . . . . . . . . . . . . . . . . . . . . 25 13.1.6. Attributes . . . . . . . . . . . . . . . . . . . . . 26
14.1.6. Attributes . . . . . . . . . . . . . . . . . . . . . 25 13.1.7. Element . . . . . . . . . . . . . . . . . . . . . . 26
14.1.7. Element . . . . . . . . . . . . . . . . . . . . . . 26 13.1.8. Element . . . . . . . . . . . . . . . . . . . . . . 26
14.1.8. Element . . . . . . . . . . . . . . . . . . . . . . 26 13.1.9. Attributes . . . . . . . . . . . . . . . . . . . . . 26
14.1.9. Attributes . . . . . . . . . . . . . . . . . . . . . 26 13.1.10. XML Schema for EBML Schema . . . . . . . . . . . . . 27
14.1.10. XML Schema for EBML Schema . . . . . . . . . . . . . 26 13.1.11. EBML Schema Example . . . . . . . . . . . . . . . . 28
14.1.11. EBML Schema Example . . . . . . . . . . . . . . . . 28 13.1.12. Identically Recurring Elements . . . . . . . . . . . 29
14.1.12. Identically Recurring Elements . . . . . . . . . . . 29 13.1.13. Expression of range . . . . . . . . . . . . . . . . 30
14.1.13. Expression of range . . . . . . . . . . . . . . . . 29 13.1.14. Textual expression of floats . . . . . . . . . . . . 30
14.1.14. Textual expression of floats . . . . . . . . . . . . 30 13.1.15. Note on the use of default attributes to define
14.1.15. Note on the use of default attributes to define
Mandatory EBML Elements . . . . . . . . . . . . . . 31 Mandatory EBML Elements . . . . . . . . . . . . . . 31
14.2. EBML Header Elements . . . . . . . . . . . . . . . . . . 31 13.2. EBML Header Elements . . . . . . . . . . . . . . . . . . 32
14.2.1. EBML Element . . . . . . . . . . . . . . . . . . . . 31 13.2.1. EBML Element . . . . . . . . . . . . . . . . . . . . 32
14.2.2. EBMLVersion Element . . . . . . . . . . . . . . . . 32 13.2.2. EBMLVersion Element . . . . . . . . . . . . . . . . 32
14.2.3. EBMLReadVersion Element . . . . . . . . . . . . . . 32 13.2.3. EBMLReadVersion Element . . . . . . . . . . . . . . 33
14.2.4. EBMLMaxIDLength Element . . . . . . . . . . . . . . 33 13.2.4. EBMLMaxIDLength Element . . . . . . . . . . . . . . 33
14.2.5. EBMLMaxSizeLength Element . . . . . . . . . . . . . 33 13.2.5. EBMLMaxSizeLength Element . . . . . . . . . . . . . 34
14.2.6. DocType Element . . . . . . . . . . . . . . . . . . 34 13.2.6. DocType Element . . . . . . . . . . . . . . . . . . 34
14.2.7. DocTypeVersion Element . . . . . . . . . . . . . . . 34 13.2.7. DocTypeVersion Element . . . . . . . . . . . . . . . 35
14.2.8. DocTypeReadVersion Element . . . . . . . . . . . . . 35 13.2.8. DocTypeReadVersion Element . . . . . . . . . . . . . 35
14.3. Global Elements . . . . . . . . . . . . . . . . . . . . 35 13.3. Global Elements . . . . . . . . . . . . . . . . . . . . 36
14.3.1. CRC-32 Element . . . . . . . . . . . . . . . . . . . 35 13.3.1. CRC-32 Element . . . . . . . . . . . . . . . . . . . 36
14.3.2. Void Element . . . . . . . . . . . . . . . . . . . . 36 13.3.2. Void Element . . . . . . . . . . . . . . . . . . . . 36
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 14. Considerations for Reading EBML Data . . . . . . . . . . . . 37
15.1. Normative References . . . . . . . . . . . . . . . . . . 36 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
15.2. Informative References . . . . . . . . . . . . . . . . . 37 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 38
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38 16.1. Normative References . . . . . . . . . . . . . . . . . . 38
16.2. Informative References . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction 1. Introduction
"EBML", short for Extensible Binary Meta Language, specifies a binary "EBML", short for Extensible Binary Meta Language, specifies a binary
and octet (byte) aligned format inspired by the principle of XML (a and octet (byte) aligned format inspired by the principle of XML (a
framework for structuring data). framework for structuring data).
The goal of this document is to define a generic, binary, space- The goal of this document is to define a generic, binary, space-
efficient format that can be used to define more complex formats efficient format that can be used to define more complex formats
(such as containers for multimedia content) using an "EBML Schema". (such as containers for multimedia content) using an "EBML Schema".
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o Data contained within a "Master Element" which is not itself part o Data contained within a "Master Element" which is not itself part
of an "EBML Element". of an "EBML Element".
o Extraneous copies of "Identically Recurring Element". o Extraneous copies of "Identically Recurring Element".
o Copies of "Identically Recurring Element" within a "Parent o Copies of "Identically Recurring Element" within a "Parent
Element" that contain invalid "CRC-32 Elements". Element" that contain invalid "CRC-32 Elements".
o Use of "Void Elements". o Use of "Void Elements".
4. IANA Considerations 4. Structure
This document has no IANA actions.
5. Structure
"EBML" uses a system of "Elements" to compose an "EBML Document". "EBML" uses a system of "Elements" to compose an "EBML Document".
"EBML Elements" incorporate three parts: an "Element ID", an "Element "EBML Elements" incorporate three parts: an "Element ID", an "Element
Data Size", and "Element Data". The "Element Data", which is Data Size", and "Element Data". The "Element Data", which is
described by the "Element ID", includes either binary data, one or described by the "Element ID", includes either binary data, one or
many other "EBML Elements", or both. many other "EBML Elements", or both.
6. Variable Size Integer 5. Variable Size Integer
The "Element ID" and "Element Data Size" are both encoded as a The "Element ID" and "Element Data Size" are both encoded as a
"Variable Size Integer", developed according to a UTF-8 like system. "Variable Size Integer", developed according to a UTF-8 like system.
The "Variable Size Integer" is composed of a "VINT_WIDTH", The "Variable Size Integer" is composed of a "VINT_WIDTH",
"VINT_MARKER", and "VINT_DATA", in that order. "Variable Size "VINT_MARKER", and "VINT_DATA", in that order. "Variable Size
Integers" MUST left-pad the "VINT_DATA" value with zero bits so that Integers" MUST left-pad the "VINT_DATA" value with zero bits so that
the whole "Variable Size Integer" is octet-aligned. "Variable Size the whole "Variable Size Integer" is octet-aligned. "Variable Size
Integer" will be referred to as "VINT" for shorthand. Integer" will be referred to as "VINT" for shorthand.
6.1. VINT_WIDTH 5.1. VINT_WIDTH
Each "Variable Size Integer" begins with a "VINT_WIDTH" which Each "Variable Size Integer" begins with a "VINT_WIDTH" which
consists of zero or many zero-value bits. The count of consecutive consists of zero or many zero-value bits. The count of consecutive
zero-values of the "VINT_WIDTH" plus one equals the length in octets zero-values of the "VINT_WIDTH" plus one equals the length in octets
of the "Variable Size Integer". For example, a "Variable Size of the "Variable Size Integer". For example, a "Variable Size
Integer" that starts with a "VINT_WIDTH" which contains zero Integer" that starts with a "VINT_WIDTH" which contains zero
consecutive zero-value bits is one octet in length and a "Variable consecutive zero-value bits is one octet in length and a "Variable
Size Integer" that starts with one consecutive zero-value bit is two Size Integer" that starts with one consecutive zero-value bit is two
octets in length. The "VINT_WIDTH" MUST only contain zero-value bits octets in length. The "VINT_WIDTH" MUST only contain zero-value bits
or be empty. or be empty.
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Within the "EBML Header" the "VINT_WIDTH" MUST NOT exceed three bits Within the "EBML Header" the "VINT_WIDTH" MUST NOT exceed three bits
in length (meaning that the "Variable Size Integer" MUST NOT exceed in length (meaning that the "Variable Size Integer" MUST NOT exceed
four octets in length). Within the "EBML Body", when a "VINT" is four octets in length). Within the "EBML Body", when a "VINT" is
used to express an "Element ID", the maximum length allowed for the used to express an "Element ID", the maximum length allowed for the
"VINT_WIDTH" is one less than the value set in the "EBMLMaxIDLength "VINT_WIDTH" is one less than the value set in the "EBMLMaxIDLength
Element". Within the "EBML Body", when a "VINT" is used to express Element". Within the "EBML Body", when a "VINT" is used to express
an "Element Data Size", the maximum length allowed for the an "Element Data Size", the maximum length allowed for the
"VINT_WIDTH" is one less than the value set in the "EBMLMaxSizeLength "VINT_WIDTH" is one less than the value set in the "EBMLMaxSizeLength
Element". Element".
6.2. VINT_MARKER 5.2. VINT_MARKER
The "VINT_MARKER" serves as a separator between the "VINT_WIDTH" and The "VINT_MARKER" serves as a separator between the "VINT_WIDTH" and
"VINT_DATA". Each "Variable Size Integer" MUST contain exactly one "VINT_DATA". Each "Variable Size Integer" MUST contain exactly one
"VINT_MARKER". The "VINT_MARKER" MUST be one bit in length and "VINT_MARKER". The "VINT_MARKER" MUST be one bit in length and
contain a bit with a value of one. The first bit with a value of one contain a bit with a value of one. The first bit with a value of one
within the "Variable Size Integer" is the "VINT_MARKER". within the "Variable Size Integer" is the "VINT_MARKER".
6.3. VINT_DATA 5.3. VINT_DATA
The "VINT_DATA" portion of the "Variable Size Integer" includes all The "VINT_DATA" portion of the "Variable Size Integer" includes all
data that follows (but not including) the "VINT_MARKER" until end of data that follows (but not including) the "VINT_MARKER" until end of
the "Variable Size Integer" whose length is derived from the the "Variable Size Integer" whose length is derived from the
"VINT_WIDTH". The bits required for the "VINT_WIDTH" and the "VINT_WIDTH". The bits required for the "VINT_WIDTH" and the
"VINT_MARKER" combined use one out of eight bits of the total length "VINT_MARKER" combined use one out of eight bits of the total length
of the "Variable Size Integer". Thus a "Variable Size Integer" of 1 of the "Variable Size Integer". Thus a "Variable Size Integer" of 1
octet length supplies 7 bits for "VINT_DATA", a 2 octet length octet length supplies 7 bits for "VINT_DATA", a 2 octet length
supplies 14 bits for "VINT_DATA", and a 3 octet length supplies 21 supplies 14 bits for "VINT_DATA", and a 3 octet length supplies 21
bits for "VINT_DATA". If the number of bits required for "VINT_DATA" bits for "VINT_DATA". If the number of bits required for "VINT_DATA"
are less than the bit size of "VINT_DATA", then "VINT_DATA" SHOULD be are less than the bit size of "VINT_DATA", then "VINT_DATA" SHOULD be
zero-padded to the left to a size that fits. The "VINT_DATA" value zero-padded to the left to a size that fits. The "VINT_DATA" value
MUST be expressed as a big-endian unsigned integer. MUST be expressed as a big-endian unsigned integer.
6.4. VINT Examples 5.4. VINT Examples
This table shows examples of "Variable Size Integers" with lengths This table shows examples of "Variable Size Integers" with lengths
from 1 to 5 octets. The Size column refers to the size of the from 1 to 5 octets. The Size column refers to the size of the
"VINT_DATA" in bits. The Representation column depicts a binary "VINT_DATA" in bits. The Representation column depicts a binary
expression of "Variable Size Integers" where "VINT_WIDTH" is depicted expression of "Variable Size Integers" where "VINT_WIDTH" is depicted
by '0', the "VINT_MARKER" as '1', and the "VINT_DATA" as 'x'. by '0', the "VINT_MARKER" as '1', and the "VINT_DATA" as 'x'.
+-------------+------+----------------------------------------------+ +-------------+------+----------------------------------------------+
| Octet | Size | Representation | | Octet | Size | Representation |
| Length | | | | Length | | |
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| Binary Value | Octet Length | As Represented in Variable Size | | Binary Value | Octet Length | As Represented in Variable Size |
| | | Integer | | | | Integer |
+--------------+--------------+-------------------------------------+ +--------------+--------------+-------------------------------------+
| 10 | 1 | 1000 0010 | | 10 | 1 | 1000 0010 |
| 10 | 2 | 0100 0000 0000 0010 | | 10 | 2 | 0100 0000 0000 0010 |
| 10 | 3 | 0010 0000 0000 0000 0000 0010 | | 10 | 3 | 0010 0000 0000 0000 0000 0010 |
| 10 | 4 | 0001 0000 0000 0000 0000 0000 0000 | | 10 | 4 | 0001 0000 0000 0000 0000 0000 0000 |
| | | 0010 | | | | 0010 |
+--------------+--------------+-------------------------------------+ +--------------+--------------+-------------------------------------+
7. Element ID 6. Element ID
The "Element ID" MUST be encoded as a "Variable Size Integer". By The "Element ID" MUST be encoded as a "Variable Size Integer". By
default, "Element IDs" are encoded in lengths from one octet to four default, "Element IDs" are encoded in lengths from one octet to four
octets, although "Element IDs" of greater lengths are used if the octets, although "Element IDs" of greater lengths are used if the
octet length of the longest "Element ID" of the "EBML Document" is octet length of the longest "Element ID" of the "EBML Document" is
declared in the "EBMLMaxIDLength Element" of the "EBML Header" (see declared in the "EBMLMaxIDLength Element" of the "EBML Header" (see
Section 14.2.4). The "VINT_DATA" component of the "Element ID" MUST Section 13.2.4). The "VINT_DATA" component of the "Element ID" MUST
NOT be either defined or written as either all zero values or all one NOT be either defined or written as either all zero values or all one
values. Any "Element ID" with the "VINT_DATA" component set as all values. Any "Element ID" with the "VINT_DATA" component set as all
zero values or all one values MUST be ignored and MUST NOT be zero values or all one values MUST be ignored and MUST NOT be
considered an error in the "EBML Document". The "VINT_DATA" considered an error in the "EBML Document". The "VINT_DATA"
component of the "Element ID" MUST be encoded at the shortest valid component of the "Element ID" MUST be encoded at the shortest valid
length. For example, an "Element ID" with binary encoding of "1011 length. For example, an "Element ID" with binary encoding of "1011
1111" is valid, whereas an "Element ID" with binary encoding of "0100 1111" is valid, whereas an "Element ID" with binary encoding of "0100
0000 0011 1111" stores a semantically equal "VINT_DATA" but is 0000 0011 1111" stores a semantically equal "VINT_DATA" but is
invalid because a shorter "VINT" encoding is possible. Additionally, invalid because a shorter "VINT" encoding is possible. Additionally,
an "Element ID" with binary encoding of "1111 1111" is invalid since an "Element ID" with binary encoding of "1111 1111" is invalid since
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+------------+--------------+--------------------------------+ +------------+--------------+--------------------------------+
| EBML Class | Octet Length | Number of Possible Element IDs | | EBML Class | Octet Length | Number of Possible Element IDs |
+------------+--------------+--------------------------------+ +------------+--------------+--------------------------------+
| Class A | 1 | 2^7 - 2 = 126 | | Class A | 1 | 2^7 - 2 = 126 |
| Class B | 2 | 2^14 - 2^7 - 1 = 16,255 | | Class B | 2 | 2^14 - 2^7 - 1 = 16,255 |
| Class C | 3 | 2^21 - 2^14 - 1 = 2,080,767 | | Class C | 3 | 2^21 - 2^14 - 1 = 2,080,767 |
| Class D | 4 | 2^28 - 2^21 - 1 = 266,338,303 | | Class D | 4 | 2^28 - 2^21 - 1 = 266,338,303 |
+------------+--------------+--------------------------------+ +------------+--------------+--------------------------------+
8. Element Data Size 7. Element Data Size
The "Element Data Size" expresses the length in octets of "Element The "Element Data Size" expresses the length in octets of "Element
Data". The "Element Data Size" itself MUST be encoded as a "Variable Data". The "Element Data Size" itself MUST be encoded as a "Variable
Size Integer". By default, "Element Data Sizes" can be encoded in Size Integer". By default, "Element Data Sizes" can be encoded in
lengths from one octet to eight octets, although "Element Data Sizes" lengths from one octet to eight octets, although "Element Data Sizes"
of greater lengths MAY be used if the octet length of the longest of greater lengths MAY be used if the octet length of the longest
"Element Data Size" of the "EBML Document" is declared in the "Element Data Size" of the "EBML Document" is declared in the
"EBMLMaxSizeLength Element" of the "EBML Header" (see "EBMLMaxSizeLength Element" of the "EBML Header" (see
Section 14.2.5). Unlike the "VINT_DATA" of the "Element ID", the Section 13.2.5). Unlike the "VINT_DATA" of the "Element ID", the
"VINT_DATA" component of the "Element Data Size" is not mandated to "VINT_DATA" component of the "Element Data Size" is not mandated to
be encoded at the shortest valid length. For example, an "Element be encoded at the shortest valid length. For example, an "Element
Data Size" with binary encoding of "1011 1111" or a binary encoding Data Size" with binary encoding of "1011 1111" or a binary encoding
of "0100 0000 0011 1111" are both valid "Element Data Sizes" and both of "0100 0000 0011 1111" are both valid "Element Data Sizes" and both
store a semantically equal value (both "0b00000000111111" and store a semantically equal value (both "0b00000000111111" and
"0b0111111", the "VINT_DATA" sections of the examples, represent the "0b0111111", the "VINT_DATA" sections of the examples, represent the
integer 63). integer 63).
Although an "Element ID" with all "VINT_DATA" bits set to zero is Although an "Element ID" with all "VINT_DATA" bits set to zero is
invalid, an "Element Data Size" with all "VINT_DATA" bits set to zero invalid, an "Element Data Size" with all "VINT_DATA" bits set to zero
is allowed for "EBML Element Types" which do not mandate a non-zero is allowed for "EBML Element Types" which do not mandate a non-zero
length (see Section 9). An "Element Data Size" with all "VINT_DATA" length (see Section 8). An "Element Data Size" with all "VINT_DATA"
bits set to zero indicates that the "Element Data" is zero octets in bits set to zero indicates that the "Element Data" is zero octets in
length. Such an "EBML Element" is referred to as an "Empty Element". length. Such an "EBML Element" is referred to as an "Empty Element".
If an "Empty Element" has a "default" value declared then the "EBML If an "Empty Element" has a "default" value declared then the "EBML
Reader" MUST interpret the value of the "Empty Element" as the Reader" MUST interpret the value of the "Empty Element" as the
"default" value. If an "Empty Element" has no "default" value "default" value. If an "Empty Element" has no "default" value
declared then the "EBML Reader" MUST interpret the value of the declared then the "EBML Reader" MUST interpret the value of the
"Empty Element" as defined as part of the definition of the "Empty Element" as defined as part of the definition of the
corresponding "EBML Element Type" associated with the "Element ID". corresponding "EBML Element Type" associated with the "Element ID".
An "Element Data Size" with all "VINT_DATA" bits set to one is An "Element Data Size" with all "VINT_DATA" bits set to one is
reserved as an indicator that the size of the "EBML Element" is reserved as an indicator that the size of the "EBML Element" is
unknown. The only reserved value for the "VINT_DATA" of "Element unknown. The only reserved value for the "VINT_DATA" of "Element
Data Size" is all bits set to one. An "EBML Element" with an unknown Data Size" is all bits set to one. An "EBML Element" with an unknown
"Element Data Size" is referred to as an "Unknown-Sized Element". "Element Data Size" is referred to as an "Unknown-Sized Element".
Only "Master Elements" SHALL be "Unknown-Sized Elements". "Master Only "Master Elements" SHALL be "Unknown-Sized Elements". "Master
Elements" MUST NOT use an unknown size unless the Elements" MUST NOT use an unknown size unless the
"unknownsizeallowed" attribute of their "EBML Schema" is set to true "unknownsizeallowed" attribute of their "EBML Schema" is set to true
(see Section 14.1.4.10). The use of "Unknown-Sized Elements" allows (see Section 13.1.4.10). The use of "Unknown-Sized Elements" allows
for an "EBML Element" to be written and read before the size of the for an "EBML Element" to be written and read before the size of the
"EBML Element" is known. "Unknown-Sized Element" MUST NOT be used or "EBML Element" is known. "Unknown-Sized Element" MUST NOT be used or
defined unnecessarily; however if the "Element Data Size" is not defined unnecessarily; however if the "Element Data Size" is not
known before the "Element Data" is written, such as in some cases of known before the "Element Data" is written, such as in some cases of
data streaming, then "Unknown-Sized Elements" MAY be used. The end data streaming, then "Unknown-Sized Elements" MAY be used. The end
of an "Unknown-Sized Element" is determined by whichever comes first: of an "Unknown-Sized Element" is determined by whichever comes first:
the end of the file or the beginning of the next "EBML Element", the end of the file or the beginning of the next "EBML Element",
defined by this document or the corresponding "EBML Schema", that is defined by this document or the corresponding "EBML Schema", that is
not independently valid as "Descendant Element" of the "Unknown-Sized not independently valid as "Descendant Element" of the "Unknown-Sized
Element". Element".
skipping to change at page 12, line 47 skipping to change at page 12, line 47
+------------+-------------+----------------+-----------------------+ +------------+-------------+----------------+-----------------------+
| VINT_WIDTH | VINT_MARKER | VINT_DATA | Element Data Size | | VINT_WIDTH | VINT_MARKER | VINT_DATA | Element Data Size |
| | | | Status | | | | | Status |
+------------+-------------+----------------+-----------------------+ +------------+-------------+----------------+-----------------------+
| | 1 | 1111111 | Reserved (meaning | | | 1 | 1111111 | Reserved (meaning |
| | | | Unknown) | | | | | Unknown) |
| 0 | 1 | 00000001111111 | Valid (meaning 127 | | 0 | 1 | 00000001111111 | Valid (meaning 127 |
| | | | octets) | | | | | octets) |
+------------+-------------+----------------+-----------------------+ +------------+-------------+----------------+-----------------------+
9. EBML Element Types 8. EBML Element Types
"EBML Elements" are defined by an "EBML Schema" which MUST declare "EBML Elements" are defined by an "EBML Schema" which MUST declare
one of the following "EBML Element Types" for each "EBML Element". one of the following "EBML Element Types" for each "EBML Element".
An "EBML Element Type" defines a concept of storing data within an An "EBML Element Type" defines a concept of storing data within an
"EBML Element" that describes such characteristics as length, "EBML Element" that describes such characteristics as length,
endianness, and definition. endianness, and definition.
"EBML Elements" which are defined as a "Signed Integer Element", "EBML Elements" which are defined as a "Signed Integer Element",
"Unsigned Integer Element", "Float Element", or "Date Element" use "Unsigned Integer Element", "Float Element", or "Date Element" use
big endian storage. big endian storage.
9.1. Signed Integer Element 8.1. Signed Integer Element
A "Signed Integer Element" MUST declare a length from zero to eight A "Signed Integer Element" MUST declare a length from zero to eight
octets. If the "EBML Element" is not defined to have a "default" octets. If the "EBML Element" is not defined to have a "default"
value, then a "Signed Integer Element" with a zero-octet length value, then a "Signed Integer Element" with a zero-octet length
represents an integer value of zero. represents an integer value of zero.
A "Signed Integer Element" stores an integer (meaning that it can be A "Signed Integer Element" stores an integer (meaning that it can be
written without a fractional component) which could be negative, written without a fractional component) which could be negative,
positive, or zero. Signed Integers MUST be stored with two's positive, or zero. Signed Integers MUST be stored with two's
complement notation with the leftmost bit being the sign bit. complement notation with the leftmost bit being the sign bit.
Because "EBML" limits Signed Integers to 8 octets in length a "Signed Because "EBML" limits Signed Integers to 8 octets in length a "Signed
Integer Element" stores a number from -9,223,372,036,854,775,808 to Integer Element" stores a number from -9,223,372,036,854,775,808 to
+9,223,372,036,854,775,807. +9,223,372,036,854,775,807.
9.2. Unsigned Integer Element 8.2. Unsigned Integer Element
An "Unsigned Integer Element" MUST declare a length from zero to An "Unsigned Integer Element" MUST declare a length from zero to
eight octets. If the "EBML Element" is not defined to have a eight octets. If the "EBML Element" is not defined to have a
"default" value, then an "Unsigned Integer Element" with a zero-octet "default" value, then an "Unsigned Integer Element" with a zero-octet
length represents an integer value of zero. length represents an integer value of zero.
An "Unsigned Integer Element" stores an integer (meaning that it can An "Unsigned Integer Element" stores an integer (meaning that it can
be written without a fractional component) which could be positive or be written without a fractional component) which could be positive or
zero. Because "EBML" limits Unsigned Integers to 8 octets in length zero. Because "EBML" limits Unsigned Integers to 8 octets in length
an "Unsigned Integer Element" stores a number from 0 to an "Unsigned Integer Element" stores a number from 0 to
18,446,744,073,709,551,615. 18,446,744,073,709,551,615.
9.3. Float Element 8.3. Float Element
A "Float Element" MUST declare a length of either zero octets (0 A "Float Element" MUST declare a length of either zero octets (0
bit), four octets (32 bit) or eight octets (64 bit). If the "EBML bit), four octets (32 bit) or eight octets (64 bit). If the "EBML
Element" is not defined to have a "default" value, then a "Float Element" is not defined to have a "default" value, then a "Float
Element" with a zero-octet length represents a numerical value of Element" with a zero-octet length represents a numerical value of
zero. zero.
A "Float Element" stores a floating-point number as defined in A "Float Element" stores a floating-point number as defined in
[IEEE.754.1985]. [IEEE.754.1985].
9.4. String Element 8.4. String Element
A "String Element" MUST declare a length in octets from zero to A "String Element" MUST declare a length in octets from zero to
"VINTMAX". If the "EBML Element" is not defined to have a "default" "VINTMAX". If the "EBML Element" is not defined to have a "default"
value, then a "String Element" with a zero-octet length represents an value, then a "String Element" with a zero-octet length represents an
empty string. empty string.
A "String Element" MUST either be empty (zero-length) or contain A "String Element" MUST either be empty (zero-length) or contain
printable ASCII characters [RFC0020] in the range of "0x20" to printable ASCII characters [RFC0020] in the range of "0x20" to
"0x7E", with an exception made for termination (see Section 10). "0x7E", with an exception made for termination (see Section 9).
9.5. UTF-8 Element 8.5. UTF-8 Element
A "UTF-8 Element" MUST declare a length in octets from zero to A "UTF-8 Element" MUST declare a length in octets from zero to
"VINTMAX". If the "EBML Element" is not defined to have a "default" "VINTMAX". If the "EBML Element" is not defined to have a "default"
value, then a "UTF-8 Element" with a zero-octet length represents an value, then a "UTF-8 Element" with a zero-octet length represents an
empty string. empty string.
A "UTF-8 Element" contains only a valid Unicode string as defined in A "UTF-8 Element" contains only a valid Unicode string as defined in
[RFC3629], with an exception made for termination (see Section 10). [RFC3629], with an exception made for termination (see Section 9).
9.6. Date Element 8.6. Date Element
A "Date Element" MUST declare a length of either zero octets or eight A "Date Element" MUST declare a length of either zero octets or eight
octets. If the "EBML Element" is not defined to have a "default" octets. If the "EBML Element" is not defined to have a "default"
value, then a "Date Element" with a zero-octet length represents a value, then a "Date Element" with a zero-octet length represents a
timestamp of 2001-01-01T00:00:00.000000000 UTC [RFC3339]. timestamp of 2001-01-01T00:00:00.000000000 UTC [RFC3339].
The "Date Element" stores an integer in the same format as the The "Date Element" stores an integer in the same format as the
"Signed Integer Element" that expresses a point in time referenced in "Signed Integer Element" that expresses a point in time referenced in
nanoseconds from the precise beginning of the third millennium of the nanoseconds from the precise beginning of the third millennium of the
Gregorian Calendar in Coordinated Universal Time (also known as Gregorian Calendar in Coordinated Universal Time (also known as
2001-01-01T00:00:00.000000000 UTC). This provides a possible 2001-01-01T00:00:00.000000000 UTC). This provides a possible
expression of time from 1708-09-11T00:12:44.854775808 UTC to expression of time from 1708-09-11T00:12:44.854775808 UTC to
2293-04-11T11:47:16.854775807 UTC. 2293-04-11T11:47:16.854775807 UTC.
9.7. Master Element 8.7. Master Element
A "Master Element" MUST declare a length in octets from zero to A "Master Element" MUST declare a length in octets from zero to
"VINTMAX". The "Master Element" MAY also use an unknown length. See "VINTMAX". The "Master Element" MAY also use an unknown length. See
Section 8 for rules that apply to elements of unknown length. Section 7 for rules that apply to elements of unknown length.
The "Master Element" contains zero, one, or many other elements. The "Master Element" contains zero, one, or many other elements.
"EBML Elements" contained within a "Master Element" MUST have the "EBML Elements" contained within a "Master Element" MUST have the
"EBMLParentPath" of their "Element Path" equals to the "EBMLParentPath" of their "Element Path" equals to the
"EBMLReferencePath" of the "Master Element" "Element Path" (see "EBMLReferencePath" of the "Master Element" "Element Path" (see
Section 14.1.4.2). "Element Data" stored within "Master Elements" Section 13.1.4.2). "Element Data" stored within "Master Elements"
SHOULD only consist of "EBML Elements" and SHOULD NOT contain any SHOULD only consist of "EBML Elements" and SHOULD NOT contain any
data that is not part of an "EBML Element". When "EBML" is used in data that is not part of an "EBML Element". When "EBML" is used in
transmission or streaming, data that is not part of an "EBML Element" transmission or streaming, data that is not part of an "EBML Element"
is permitted to be present within a "Master Element" if is permitted to be present within a "Master Element" if
"unknownsizeallowed" is enabled within the definition for that "unknownsizeallowed" is enabled within the definition for that
"Master Element". In this case, the "EBML Reader" should skip data "Master Element". In this case, the "EBML Reader" should skip data
until a valid "Element ID" of the same "EBMLParentPath" or the next until a valid "Element ID" of the same "EBMLParentPath" or the next
upper level "Element Path" of the "Master Element" is found. What upper level "Element Path" of the "Master Element" is found. What
"Element IDs" are considered valid within a "Master Element" is "Element IDs" are considered valid within a "Master Element" is
identified by the "EBML Schema" for that version of the "EBML identified by the "EBML Schema" for that version of the "EBML
Document Type". Any data contained within a "Master Element" that is Document Type". Any data contained within a "Master Element" that is
not part of a "Child Element" MUST be ignored. not part of a "Child Element" MUST be ignored.
9.8. Binary Element 8.8. Binary Element
A "Binary Element" MUST declare a length in octets from zero to A "Binary Element" MUST declare a length in octets from zero to
"VINTMAX". "VINTMAX".
The contents of a "Binary Element" should not be interpreted by the The contents of a "Binary Element" should not be interpreted by the
"EBML Reader". "EBML Reader".
10. Terminating Elements 9. Terminating Elements
"Null Octets", which are octets with all bits set to zero, MAY follow "Null Octets", which are octets with all bits set to zero, MAY follow
the value of a "String Element" or "UTF-8 Element" to serve as a the value of a "String Element" or "UTF-8 Element" to serve as a
terminator. An "EBML Writer" MAY terminate a "String Element" or terminator. An "EBML Writer" MAY terminate a "String Element" or
"UTF-8 Element" with "Null Octets" in order to overwrite a stored "UTF-8 Element" with "Null Octets" in order to overwrite a stored
value with a new value of lesser length while maintaining the same value with a new value of lesser length while maintaining the same
"Element Data Size" (this can prevent the need to rewrite large "Element Data Size" (this can prevent the need to rewrite large
portions of an "EBML Document"); otherwise the use of "Null Octets" portions of an "EBML Document"); otherwise the use of "Null Octets"
within a "String Element" or "UTF-8 Element" is NOT RECOMMENDED. An within a "String Element" or "UTF-8 Element" is NOT RECOMMENDED. An
"EBML Reader" MUST consider the value of the "String Element" or "EBML Reader" MUST consider the value of the "String Element" or
skipping to change at page 16, line 5 skipping to change at page 16, line 5
+---------------------+---------------------+ +---------------------+---------------------+
| Stored Value | Semantic Meaning | | Stored Value | Semantic Meaning |
+---------------------+---------------------+ +---------------------+---------------------+
| 0x65 0x62 0x6d 0x6c | 0x65 0x62 0x6d 0x6c | | 0x65 0x62 0x6d 0x6c | 0x65 0x62 0x6d 0x6c |
| 0x65 0x62 0x00 0x6c | 0x65 0x62 | | 0x65 0x62 0x00 0x6c | 0x65 0x62 |
| 0x65 0x62 0x00 0x00 | 0x65 0x62 | | 0x65 0x62 0x00 0x00 | 0x65 0x62 |
| 0x65 0x62 | 0x65 0x62 | | 0x65 0x62 | 0x65 0x62 |
+---------------------+---------------------+ +---------------------+---------------------+
11. Guidelines for Updating Elements 10. Guidelines for Updating Elements
An EBML Document can be updated without requiring that the entire An EBML Document can be updated without requiring that the entire
EBML Document be rewritten. These recommendations describe EBML Document be rewritten. These recommendations describe
strategies to change the "Element Data" of a written "EBML Element" strategies to change the "Element Data" of a written "EBML Element"
with minimal disruption to the rest of the "EBML Document". with minimal disruption to the rest of the "EBML Document".
11.1. Reducing a Element Data in Size 10.1. Reducing a Element Data in Size
There are three methods to reduce the size of "Element Data" of a There are three methods to reduce the size of "Element Data" of a
written "EBML Element". written "EBML Element".
11.1.1. Adding a Void Element 10.1.1. Adding a Void Element
When an "EBML Element" is changed to reduce its total length by more When an "EBML Element" is changed to reduce its total length by more
than one octet, an "EBML Writer" SHOULD fill the freed space with a than one octet, an "EBML Writer" SHOULD fill the freed space with a
"Void Element". "Void Element".
11.1.2. Extending the Element Data Size 10.1.2. Extending the Element Data Size
The same value for "Element Data Size" MAY be written in variable The same value for "Element Data Size" MAY be written in variable
lengths, so for minor reductions in octet length the "Element Data lengths, so for minor reductions in octet length the "Element Data
Size" MAY be written to a longer octet length to fill the freed Size" MAY be written to a longer octet length to fill the freed
space. space.
For example, the first row of the following table depicts a "String For example, the first row of the following table depicts a "String
Element" that stores an "Element ID" (3 octets), "Element Data Size" Element" that stores an "Element ID" (3 octets), "Element Data Size"
(1 octet), and "Element Data" (4 octets). If the "Element Data" is (1 octet), and "Element Data" (4 octets). If the "Element Data" is
changed to reduce the length by one octet and if the current length changed to reduce the length by one octet and if the current length
skipping to change at page 17, line 22 skipping to change at page 17, line 22
space to add a two octet "Void Element". space to add a two octet "Void Element".
+--------+------------+-----------------+-------------+-------------+ +--------+------------+-----------------+-------------+-------------+
| Status | Element ID | Element Data | Element | Void | | Status | Element ID | Element Data | Element | Void |
| | | Size | Data | Element | | | | Size | Data | Element |
+--------+------------+-----------------+-------------+-------------+ +--------+------------+-----------------+-------------+-------------+
| Before | 0x3B4040 | 0x4003 | 0x6d6b76 | | | Before | 0x3B4040 | 0x4003 | 0x6d6b76 | |
| After | 0x3B4040 | 0x82 | 0x6869 | 0xEC80 | | After | 0x3B4040 | 0x82 | 0x6869 | 0xEC80 |
+--------+------------+-----------------+-------------+-------------+ +--------+------------+-----------------+-------------+-------------+
11.1.3. Terminating Element Data 10.1.3. Terminating Element Data
For "String Elements" and "UTF-8 Elements" the length of "Element For "String Elements" and "UTF-8 Elements" the length of "Element
Data" MAY be reduced by adding "Null Octets" to terminate the Data" MAY be reduced by adding "Null Octets" to terminate the
"Element Data" (see Section 10). "Element Data" (see Section 9).
In the following table, a four octet long "Element Data" is changed In the following table, a four octet long "Element Data" is changed
to a three octet long value followed by a "Null Octet"; the "Element to a three octet long value followed by a "Null Octet"; the "Element
Data Size" includes any "Null Octets" used to terminate "Element Data Size" includes any "Null Octets" used to terminate "Element
Data" so remains unchanged. Data" so remains unchanged.
+-------------+------------+-------------------+--------------+ +-------------+------------+-------------------+--------------+
| Status | Element ID | Element Data Size | Element Data | | Status | Element ID | Element Data Size | Element Data |
+-------------+------------+-------------------+--------------+ +-------------+------------+-------------------+--------------+
| Before edit | 0x3B4040 | 0x84 | 0x65626d6c | | Before edit | 0x3B4040 | 0x84 | 0x65626d6c |
| After edit | 0x3B4040 | 0x84 | 0x6d6b7600 | | After edit | 0x3B4040 | 0x84 | 0x6d6b7600 |
+-------------+------------+-------------------+--------------+ +-------------+------------+-------------------+--------------+
Note that this method is NOT RECOMMENDED. For reductions of one Note that this method is NOT RECOMMENDED. For reductions of one
octet, the method for "Extending the Element Data Size" SHOULD be octet, the method for "Extending the Element Data Size" SHOULD be
used. For reduction by more than one octet, the method for "Adding a used. For reduction by more than one octet, the method for "Adding a
Void Element" SHOULD be used. Void Element" SHOULD be used.
11.2. Considerations when Updating Elements with CRC 10.2. Considerations when Updating Elements with CRC
If the "Element" to be changed is a "Descendant Element" of any If the "Element" to be changed is a "Descendant Element" of any
"Master Element" that contains an "CRC-32 Element" then the "CRC-32 "Master Element" that contains an "CRC-32 Element" then the "CRC-32
Element" MUST be verified before permitting the change. Additionally Element" MUST be verified before permitting the change. Additionally
the "CRC-32 Element" value MUST be subsequently updated to reflect the "CRC-32 Element" value MUST be subsequently updated to reflect
the changed data. the changed data.
12. EBML Document 11. EBML Document
An "EBML Document" is comprised of only two components, an "EBML An "EBML Document" is comprised of only two components, an "EBML
Header" and an "EBML Body". An "EBML Document" MUST start with an Header" and an "EBML Body". An "EBML Document" MUST start with an
"EBML Header" that declares significant characteristics of the entire "EBML Header" that declares significant characteristics of the entire
"EBML Body". An "EBML Document" consists of "EBML Elements" and MUST "EBML Body". An "EBML Document" consists of "EBML Elements" and MUST
NOT contain any data that is not part of an "EBML Element". NOT contain any data that is not part of an "EBML Element".
12.1. EBML Header 11.1. EBML Header
The "EBML Header" is a declaration that provides processing The "EBML Header" is a declaration that provides processing
instructions and identification of the "EBML Body". The "EBML instructions and identification of the "EBML Body". The "EBML
Header" of an "EBML Document" is analogous to the XML Declaration of Header" of an "EBML Document" is analogous to the XML Declaration of
an XML Document. an XML Document.
The "EBML Header" documents the "EBML Schema" (also known as the The "EBML Header" documents the "EBML Schema" (also known as the
"EBML DocType") that is used to semantically interpret the structure "EBML DocType") that is used to semantically interpret the structure
and meaning of the "EBML Document". Additionally the "EBML Header" and meaning of the "EBML Document". Additionally the "EBML Header"
documents the versions of both "EBML" and the "EBML Schema" that were documents the versions of both "EBML" and the "EBML Schema" that were
used to write the "EBML Document" and the versions required to read used to write the "EBML Document" and the versions required to read
the "EBML Document". the "EBML Document".
The "EBML Header" MUST contain a single "Master Element" with an The "EBML Header" MUST contain a single "Master Element" with an
"Element Name" of "EBML" and "Element ID" of "0x1A45DFA3" (see "Element Name" of "EBML" and "Element ID" of "0x1A45DFA3" (see
Section 14.2.1) and any number of additional "EBML Elements" within Section 13.2.1) and any number of additional "EBML Elements" within
it. The "EBML Header" MUST only contain "EBML Elements" that are it. The "EBML Header" of an "EBML Document" that uses an
"EBMLVersion" of "1" MUST only contain "EBML Elements" that are
defined as part of this document. defined as part of this document.
All "EBML Elements" within the "EBML Header" MUST NOT use any All "EBML Elements" within the "EBML Header" MUST NOT use any
"Element ID" with a length greater than 4 octets. All "EBML "Element ID" with a length greater than 4 octets. All "EBML
Elements" within the "EBML Header" MUST NOT use any "Element Data Elements" within the "EBML Header" MUST NOT use any "Element Data
Size" with a length greater than 4 octets. Size" with a length greater than 4 octets.
12.2. EBML Body 11.2. EBML Body
All data of an "EBML Document" following the "EBML Header" is the All data of an "EBML Document" following the "EBML Header" is the
"EBML Body". The end of the "EBML Body", as well as the end of the "EBML Body". The end of the "EBML Body", as well as the end of the
"EBML Document" that contains the "EBML Body", is considered as "EBML Document" that contains the "EBML Body", is considered as
whichever comes first: the beginning of a new "EBML Header" at the whichever comes first: the beginning of a new "EBML Header" at the
"Root Level" or the end of the file. The "EBML Body" MUST consist "Root Level" or the end of the file. The "EBML Body" MUST consist
only of "EBML Elements" and MUST NOT contain any data that is not only of "EBML Elements" and MUST NOT contain any data that is not
part of an "EBML Element". This document defines precisely what part of an "EBML Element". This document defines precisely what
"EBML Elements" are to be used within the "EBML Header", but does not "EBML Elements" are to be used within the "EBML Header", but does not
name or define what "EBML Elements" are to be used within the "EBML name or define what "EBML Elements" are to be used within the "EBML
Body". The definition of what "EBML Elements" are to be used within Body". The definition of what "EBML Elements" are to be used within
the "EBML Body" is defined by an "EBML Schema". the "EBML Body" is defined by an "EBML Schema".
13. EBML Stream 12. EBML Stream
An "EBML Stream" is a file that consists of one or many "EBML An "EBML Stream" is a file that consists of one or many "EBML
Documents" that are concatenated together. An occurrence of a "EBML Documents" that are concatenated together. An occurrence of a "EBML
Header" at the "Root Level" marks the beginning of an "EBML Header" at the "Root Level" marks the beginning of an "EBML
Document". Document".
14. Elements semantic 13. Elements semantic
14.1. EBML Schema 13.1. EBML Schema
An "EBML Schema" is an XML Document that defines the properties, An "EBML Schema" is an XML Document that defines the properties,
arrangement, and usage of "EBML Elements" that compose a specific arrangement, and usage of "EBML Elements" that compose a specific
"EBML Document Type". The relationship of an "EBML Schema" to an "EBML Document Type". The relationship of an "EBML Schema" to an
"EBML Document" may be considered analogous to the relationship of an "EBML Document" may be considered analogous to the relationship of an
XML Schema [W3C.REC-xmlschema-0-20010502] to an XML Document XML Schema [W3C.REC-xmlschema-0-20010502] to an XML Document
[W3C.REC-xml-20081126]. An "EBML Schema" MUST be clearly associated [W3C.REC-xml-20081126]. An "EBML Schema" MUST be clearly associated
with one or many "EBML Document Types". An "EBML Schema" must be with one or many "EBML Document Types". An "EBML Schema" must be
expressed as well-formed XML. An "EBML Document Type" is identified expressed as well-formed XML. An "EBML Document Type" is identified
by a string stored within the "EBML Header" in the "DocType Element"; by a string stored within the "EBML Header" in the "DocType Element";
for example "matroska" or "webm" (see Section 14.2.6). The "DocType" for example "matroska" or "webm" (see Section 13.2.6). The "DocType"
value for an "EBML Document Type" SHOULD be unique and persistent. value for an "EBML Document Type" SHOULD be unique and persistent.
An "EBML Schema" MUST declare exactly one "EBML Element" at "Root An "EBML Schema" MUST declare exactly one "EBML Element" at "Root
Level" (referred to as the "Root Element") that MUST occur exactly Level" (referred to as the "Root Element") that MUST occur exactly
once within an "EBML Document". The "Void Element" MAY also occur at once within an "EBML Document". The "Void Element" MAY also occur at
"Root Level" but is not considered to be "Root Elements" (see "Root Level" but is not considered to be "Root Elements" (see
Section 14.3.2). Section 13.3.2).
The "EBML Schema" MUST document all Elements of the "EBML Body". The The "EBML Schema" MUST document all Elements of the "EBML Body". The
"EBML Schema" does not document "Global Elements" that are defined by "EBML Schema" does not document "Global Elements" that are defined by
this document (namely the "Void Element" and the "CRC-32 Element"). this document (namely the "Void Element" and the "CRC-32 Element").
An "EBML Schema" MAY constrain the use of "EBML Header Elements" (see An "EBML Schema" MAY constrain the use of "EBML Header Elements" (see
Section 14.2) by adding or constraining that Element's "range" Section 13.2) by adding or constraining that Element's "range"
attribute. For example, an "EBML Schema" MAY constrain the attribute. For example, an "EBML Schema" MAY constrain the
"EBMLMaxSizeLength" to a maximum value of "8" or MAY constrain the "EBMLMaxSizeLength" to a maximum value of "8" or MAY constrain the
"EBMLVersion" to only support a value of "1". If an "EBML Schema" "EBMLVersion" to only support a value of "1". If an "EBML Schema"
adopts the "EBML Header Element" as-is, then it is not REQUIRED to adopts the "EBML Header Element" as-is, then it is not REQUIRED to
document that Element within the "EBML Schema". If an "EBML Schema" document that Element within the "EBML Schema". If an "EBML Schema"
constrains the range of an "EBML Header Element", then that "Element" constrains the range of an "EBML Header Element", then that "Element"
MUST be documented within an "<element>" node of the "EBML Schema". MUST be documented within an "<element>" node of the "EBML Schema".
This document provides an example of an "EBML Schema", see This document provides an example of an "EBML Schema", see
Section 14.1.11. Section 13.1.11.
14.1.1. Element 13.1.1. Element
As an XML Document, the "EBML Schema" MUST use "<EBMLSchema>" as the As an XML Document, the "EBML Schema" MUST use "<EBMLSchema>" as the
top level element. The "<EBMLSchema>" element MAY contain top level element. The "<EBMLSchema>" element MAY contain
"<element>" sub-elements. "<element>" sub-elements.
14.1.2. Attributes 13.1.2. Attributes
Within an "EBML Schema" the "<EBMLSchema>" element uses the following Within an "EBML Schema" the "<EBMLSchema>" element uses the following
attributes: attributes:
14.1.2.1. docType 13.1.2.1. docType
The "docType" lists the official name of the "EBML Document Type" The "docType" lists the official name of the "EBML Document Type"
that is defined by the "EBML Schema"; for example, "<EBMLSchema that is defined by the "EBML Schema"; for example, "<EBMLSchema
docType="matroska">". docType="matroska">".
The "docType" attribute is REQUIRED within the "<EBMLSchema>" The "docType" attribute is REQUIRED within the "<EBMLSchema>"
Element. Element.
14.1.2.2. version 13.1.2.2. version
The "version" lists an incremental non-negative integer that The "version" lists an incremental non-negative integer that
specifies the version of the docType documented by the "EBML Schema". specifies the version of the docType documented by the "EBML Schema".
Unlike XML Schemas, an "EBML Schema" documents all versions of a Unlike XML Schemas, an "EBML Schema" documents all versions of a
docType's definition rather than using separate "EBML Schemas" for docType's definition rather than using separate "EBML Schemas" for
each version of a "docType". "EBML Elements" may be introduced and each version of a "docType". "EBML Elements" may be introduced and
deprecated by using the "minver" and "maxver" attributes of deprecated by using the "minver" and "maxver" attributes of
"<element>". "<element>".
The "version" attribute is REQUIRED within the "<EBMLSchema>" The "version" attribute is REQUIRED within the "<EBMLSchema>"
Element. Element.
14.1.3. Element 13.1.3. Element
Each "<element>" defines one "EBML Element" through the use of Each "<element>" defines one "EBML Element" through the use of
several attributes that are defined in Section 14.1.2. "EBML several attributes that are defined in Section 13.1.2. "EBML
Schemas" MAY contain additional attributes to extend the semantics Schemas" MAY contain additional attributes to extend the semantics
but MUST NOT conflict with the definitions of the "<element>" but MUST NOT conflict with the definitions of the "<element>"
attributes defined within this document. attributes defined within this document.
The "<element>" nodes contain a description of the meaning and use of The "<element>" nodes contain a description of the meaning and use of
the "EBML Element" stored within one or many "<documentation>" sub- the "EBML Element" stored within one or many "<documentation>" sub-
elements and zero or one "<restriction>" sub-element. All elements and zero or one "<restriction>" sub-element. All
"<element>" nodes MUST be sub-elements of the "<EBMLSchema>". "<element>" nodes MUST be sub-elements of the "<EBMLSchema>".
14.1.4. Attributes 13.1.4. Attributes
Within an "EBML Schema" the "<element>" uses the following attributes Within an "EBML Schema" the "<element>" uses the following attributes
to define an "EBML Element": to define an "EBML Element":
14.1.4.1. name 13.1.4.1. name
The "name" provides the official human-readable name of the "EBML The "name" provides the official human-readable name of the "EBML
Element". The value of the name MUST be in the form of characters Element". The value of the name MUST be in the form of characters
"A" to "Z", "a" to "z", "0" to "9", "-" and ".". "A" to "Z", "a" to "z", "0" to "9", "-" and ".".
The "name" attribute is REQUIRED. The "name" attribute is REQUIRED.
14.1.4.2. path 13.1.4.2. path
The path defines the allowed storage locations of the "EBML Element" The path defines the allowed storage locations of the "EBML Element"
within an "EBML Document". This path MUST be defined with the full within an "EBML Document". This path MUST be defined with the full
hierarchy of "EBML Elements" separated with a "/". The top "EBML hierarchy of "EBML Elements" separated with a "/". The top "EBML
Element" in the path hierarchy being the first in the value. The Element" in the path hierarchy being the first in the value. The
syntax of the "path" attribute is defined using this Augmented syntax of the "path" attribute is defined using this Augmented
Backus-Naur Form (ABNF) [RFC5234] with the case sensitive update Backus-Naur Form (ABNF) [RFC5234] with the case sensitive update
[RFC7405] notation: [RFC7405] notation:
The "path" attribute is REQUIRED. The "path" attribute is REQUIRED.
skipping to change at page 22, line 26 skipping to change at page 22, line 26
of this "EBML Element" within its "Parent Element". Each instance of of this "EBML Element" within its "Parent Element". Each instance of
the "Parent Element" MUST contain at least this many instances of the "Parent Element" MUST contain at least this many instances of
this "EBML Element". If the "EBML Element" has an empty this "EBML Element". If the "EBML Element" has an empty
"EBMLParentPath" then "EBMLMinOccurrence" refers to constraints on "EBMLParentPath" then "EBMLMinOccurrence" refers to constraints on
the occurrence of the "EBML Element" within the "EBML Document". If the occurrence of the "EBML Element" within the "EBML Document". If
"EBMLMinOccurrence" is not present then that "EBML Element" is "EBMLMinOccurrence" is not present then that "EBML Element" is
considered to have a "EBMLMinOccurrence" value of 0. The semantic considered to have a "EBMLMinOccurrence" value of 0. The semantic
meaning of "EBMLMinOccurrence" within an "EBML Schema" is considered meaning of "EBMLMinOccurrence" within an "EBML Schema" is considered
analogous to the meaning of "minOccurs" within an "XML Schema". analogous to the meaning of "minOccurs" within an "XML Schema".
"EBML Elements" with "EBMLMinOccurrence" set to "1" that also have a "EBML Elements" with "EBMLMinOccurrence" set to "1" that also have a
"default" value (see Section 14.1.4.8) declared are not REQUIRED to "default" value (see Section 13.1.4.8) declared are not REQUIRED to
be stored but are REQUIRED to be interpreted, see Section 14.1.15. be stored but are REQUIRED to be interpreted, see Section 13.1.15.
An "EBML Element" defined with a "EBMLMinOccurrence" value greater An "EBML Element" defined with a "EBMLMinOccurrence" value greater
than zero is called a "Mandatory EBML Element". than zero is called a "Mandatory EBML Element".
The "EBMLMaxOccurrence" represents the maximum number of occurrences The "EBMLMaxOccurrence" represents the maximum number of occurrences
of this "EBML Element" within its "Parent Element". Each instance of of this "EBML Element" within its "Parent Element". Each instance of
the "Parent Element" MUST contain at most this many instances of this the "Parent Element" MUST contain at most this many instances of this
"EBML Element". If the "EBML Element" has an empty "EBMLParentPath" "EBML Element". If the "EBML Element" has an empty "EBMLParentPath"
then "EBMLMaxOccurrence" refers to constraints on the occurrence of then "EBMLMaxOccurrence" refers to constraints on the occurrence of
the "EBML Element" within the "EBML Document". If the "EBML Element" within the "EBML Document". If
"EBMLMaxOccurrence" is not present then that "EBML Element" is "EBMLMaxOccurrence" is not present then that "EBML Element" is
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"EBMLMaxOccurrence" within an "EBML Schema path" is considered "EBMLMaxOccurrence" within an "EBML Schema path" is considered
analogous to the meaning of "maxOccurs" within an "XML Schema". analogous to the meaning of "maxOccurs" within an "XML Schema".
The "VariableParentOccurrence" part is interpreted as an ABNF The "VariableParentOccurrence" part is interpreted as an ABNF
Variable Repetition. The repetition amounts correspond to the amount Variable Repetition. The repetition amounts correspond to the amount
of unspecified "Parent Element" levels there can be between the of unspecified "Parent Element" levels there can be between the
"EBMLFixedParent" and the actual "EBMLElementPath". "EBMLFixedParent" and the actual "EBMLElementPath".
If the path contains an "EBMLPathAtomRecursive" part, the "EBML If the path contains an "EBMLPathAtomRecursive" part, the "EBML
Element" can occur within itself recursively (see the Element" can occur within itself recursively (see the
Section 14.1.4.11). Section 13.1.4.11).
14.1.4.3. id 13.1.4.3. id
The "Element ID" encoded as a "Variable Size Integer" expressed in The "Element ID" encoded as a "Variable Size Integer" expressed in
hexadecimal notation prefixed by a "0x" that is read and stored in hexadecimal notation prefixed by a "0x" that is read and stored in
big-endian order. To reduce the risk of false positives while big-endian order. To reduce the risk of false positives while
parsing "EBML Streams", the "Element IDs" of the "Root Element" and parsing "EBML Streams", the "Element IDs" of the "Root Element" and
"Top-Level Elements" SHOULD be at least 4 octets in length. "Element "Top-Level Elements" SHOULD be at least 4 octets in length. "Element
IDs" defined for use at "Root Level" or directly under the "Root IDs" defined for use at "Root Level" or directly under the "Root
Level" MAY use shorter octet lengths to facilitate padding and Level" MAY use shorter octet lengths to facilitate padding and
optimize edits to "EBML Documents"; for instance, the "Void Element" optimize edits to "EBML Documents"; for instance, the "Void Element"
uses an "Element ID" with a one octet length to allow its usage in uses an "Element ID" with a one octet length to allow its usage in
more writing and editing scenarios. more writing and editing scenarios.
The "id" attribute is REQUIRED. The "id" attribute is REQUIRED.
14.1.4.4. minOccurs 13.1.4.4. minOccurs
An integer expressing the minimum number of occurrences of this "EBML An integer expressing the minimum number of occurrences of this "EBML
Element" within its "Parent Element". The "minOccurs" value MUST be Element" within its "Parent Element". The "minOccurs" value MUST be
equal to the "EBMLMinOccurrence" value of the "path". equal to the "EBMLMinOccurrence" value of the "path".
The "minOccurs" attribute is OPTIONAL. If the "minOccurs" attribute The "minOccurs" attribute is OPTIONAL. If the "minOccurs" attribute
is not present then that "EBML Element" is considered to have a is not present then that "EBML Element" is considered to have a
"minOccurs" value of 0. "minOccurs" value of 0.
14.1.4.5. maxOccurs 13.1.4.5. maxOccurs
An integer expressing the maximum number of occurrences of this "EBML An integer expressing the maximum number of occurrences of this "EBML
Element" within its "Parent Element". The "maxOccurs" value MUST be Element" within its "Parent Element". The "maxOccurs" value MUST be
equal to the "EBMLMaxOccurrence" value of the "path". equal to the "EBMLMaxOccurrence" value of the "path".
The "maxOccurs" attribute is OPTIONAL. If the "maxOccurs" attribute The "maxOccurs" attribute is OPTIONAL. If the "maxOccurs" attribute
is not present then that "EBML Element" is considered to have no is not present then that "EBML Element" is considered to have no
maximum occurrence, similar to "unbounded" in the XML world. maximum occurrence, similar to "unbounded" in the XML world.
14.1.4.6. range 13.1.4.6. range
A numerical range for "EBML Elements" which are of numerical types A numerical range for "EBML Elements" which are of numerical types
(Unsigned Integer, Signed Integer, Float, and Date). If specified (Unsigned Integer, Signed Integer, Float, and Date). If specified
the value of the "EBML Element" MUST be within the defined range. the value of the "EBML Element" MUST be within the defined range.
See Section 14.1.13 for rules applied to expression of range values. See Section 13.1.13 for rules applied to expression of range values.
The "range" attribute is OPTIONAL. If the "range" attribute is not The "range" attribute is OPTIONAL. If the "range" attribute is not
present then any value legal for the "type" attribute is valid. present then any value legal for the "type" attribute is valid.
14.1.4.7. size 13.1.4.7. size
A value to express the valid length of the "Element Data" as written A value to express the valid length of the "Element Data" as written
measured in octets. The "size" provides a constraint in addition to measured in octets. The "size" provides a constraint in addition to
the Length value of the definition of the corresponding "EBML Element the Length value of the definition of the corresponding "EBML Element
Type". This "size" MUST be expressed as either a non-negative Type". This "size" MUST be expressed as either a non-negative
integer or a range (see Section 14.1.13) that consists of only non- integer or a range (see Section 13.1.13) that consists of only non-
negative integers and valid operators. negative integers and valid operators.
The "size" attribute is OPTIONAL. If the "size" attribute is not The "size" attribute is OPTIONAL. If the "size" attribute is not
present for that "EBML Element" then that "EBML Element" is only present for that "EBML Element" then that "EBML Element" is only
limited in size by the definition of the associated "EBML Element limited in size by the definition of the associated "EBML Element
Type". Type".
14.1.4.8. default 13.1.4.8. default
If an "Element" is mandatory (has a "EBMLMinOccurrence" value greater If an "Element" is mandatory (has a "EBMLMinOccurrence" value greater
than zero) but not written within its "Parent Element" or stored as than zero) but not written within its "Parent Element" or stored as
an "Empty Element", then the "EBML Reader" of the "EBML Document" an "Empty Element", then the "EBML Reader" of the "EBML Document"
MUST semantically interpret the "EBML Element" as present with this MUST semantically interpret the "EBML Element" as present with this
specified default value for the "EBML Element". "EBML Elements" that specified default value for the "EBML Element". "EBML Elements" that
are "Master Elements" MUST NOT declare a "default" value. "EBML are "Master Elements" MUST NOT declare a "default" value. "EBML
Elements" with a "minOccurs" value greater than 1 MUST NOT declare a Elements" with a "minOccurs" value greater than 1 MUST NOT declare a
"default" value. "default" value.
The "default" attribute is OPTIONAL. The "default" attribute is OPTIONAL.
14.1.4.9. type 13.1.4.9. type
The "type" MUST be set to one of the following values: 'integer' The "type" MUST be set to one of the following values: 'integer'
(signed integer), 'uinteger' (unsigned integer), 'float', 'string', (signed integer), 'uinteger' (unsigned integer), 'float', 'string',
'date', 'utf-8', 'master', or 'binary'. The content of each "type" 'date', 'utf-8', 'master', or 'binary'. The content of each "type"
is defined within Section 9. is defined within Section 8.
The "type" attribute is REQUIRED. The "type" attribute is REQUIRED.
14.1.4.10. unknownsizeallowed 13.1.4.10. unknownsizeallowed
A boolean to express if an "EBML Element" MAY be used as an "Unknown- A boolean to express if an "EBML Element" MAY be used as an "Unknown-
Sized Element" (having all "VINT_DATA" bits of "Element Data Size" Sized Element" (having all "VINT_DATA" bits of "Element Data Size"
set to 1). "EBML Elements" that are not "Master Elements" MUST NOT set to 1). "EBML Elements" that are not "Master Elements" MUST NOT
set "unknownsizeallowed" to true. An "EBML Element" that is defined set "unknownsizeallowed" to true. An "EBML Element" that is defined
with an "unknownsizeallowed" attribute set to 1 MUST also have the with an "unknownsizeallowed" attribute set to 1 MUST also have the
"unknownsizeallowed" attribute of its "Parent Element" set to 1. "unknownsizeallowed" attribute of its "Parent Element" set to 1.
The "unknownsizeallowed" attribute is OPTIONAL. If the The "unknownsizeallowed" attribute is OPTIONAL. If the
"unknownsizeallowed" attribute is not used then that "EBML Element" "unknownsizeallowed" attribute is not used then that "EBML Element"
is not allowed to use an unknown "Element Data Size". is not allowed to use an unknown "Element Data Size".
14.1.4.11. recursive 13.1.4.11. recursive
A boolean to express if an "EBML Element" MAY be stored recursively. A boolean to express if an "EBML Element" MAY be stored recursively.
In this case the "EBML Element" MAY be stored within another "EBML In this case the "EBML Element" MAY be stored within another "EBML
Element" that has the same "Element ID". Which itself can be stored Element" that has the same "Element ID". Which itself can be stored
in an "EBML Element" that has the same "Element ID", and so on. in an "EBML Element" that has the same "Element ID", and so on.
"EBML Elements" that are not "Master Elements" MUST NOT set "EBML Elements" that are not "Master Elements" MUST NOT set
"recursive" to true. "recursive" to true.
If the "path" contains an "EBMLPathAtomRecursive" part then the If the "path" contains an "EBMLPathAtomRecursive" part then the
"recursive" value MUST be true and false otherwise. "recursive" value MUST be true and false otherwise.
The "recursive" attribute is OPTIONAL. If the "recursive" attribute The "recursive" attribute is OPTIONAL. If the "recursive" attribute
is not present then the "EBML Element" MUST NOT be used recursively. is not present then the "EBML Element" MUST NOT be used recursively.
14.1.4.12. minver 13.1.4.12. recurring
A boolean to express if an "EBML Element" is defined as an
"Identically Recurring Element" or not.
The "recurring" attribute is OPTIONAL. If the "recurring" attribute
is not present then the "EBML Element" MUST be considered to NOT be
an "Identically Recurring Element".
13.1.4.13. minver
The "minver" (minimum version) attribute stores a non-negative The "minver" (minimum version) attribute stores a non-negative
integer that represents the first version of the "docType" to support integer that represents the first version of the "docType" to support
the "EBML Element". the "EBML Element".
The "minver" attribute is OPTIONAL. If the "minver" attribute is not The "minver" attribute is OPTIONAL. If the "minver" attribute is not
present, then the "EBML Element" has a minimum version of "1". present, then the "EBML Element" has a minimum version of "1".
14.1.4.13. maxver 13.1.4.14. maxver
The "maxver" (maximum version) attribute stores a non-negative The "maxver" (maximum version) attribute stores a non-negative
integer that represents the last or most recent version of the integer that represents the last or most recent version of the
"docType" to support the element. "maxver" MUST be greater than or "docType" to support the element. "maxver" MUST be greater than or
equal to "minver". equal to "minver".
The "maxver" attribute is OPTIONAL. If the "maxver" attribute is not The "maxver" attribute is OPTIONAL. If the "maxver" attribute is not
present then the "EBML Element" has a maximum version equal to the present then the "EBML Element" has a maximum version equal to the
value stored in the "version" attribute of "<EBMLSchema>". value stored in the "version" attribute of "<EBMLSchema>".
14.1.5. Element 13.1.5. Element
The "<documentation>" element provides additional information about The "<documentation>" element provides additional information about
the "EBML Element". the "EBML Element".
14.1.6. Attributes 13.1.6. Attributes
14.1.6.1. lang 13.1.6.1. lang
A "lang" attribute which is set to the [RFC5646] value of the A "lang" attribute which is set to the [RFC5646] value of the
language of the element's documentation. language of the element's documentation.
The "lang" attribute is OPTIONAL. The "lang" attribute is OPTIONAL.
14.1.6.2. type 13.1.6.2. type
A "type" attribute distinguishes the meaning of the documentation. A "type" attribute distinguishes the meaning of the documentation.
Values for the "<documentation>" sub-element's "type" attribute MUST Values for the "<documentation>" sub-element's "type" attribute MUST
include one of the following: "definition", "rationale", "usage include one of the following: "definition", "rationale", "usage
notes", and "references". notes", and "references".
The "type" attribute is OPTIONAL. The "type" attribute is OPTIONAL.
14.1.7. Element 13.1.7. Element
The "<restriction>" element provides information about restrictions The "<restriction>" element provides information about restrictions
to the allowable values for the "EBML Element" which are listed in to the allowable values for the "EBML Element" which are listed in
"<enum>" elements. "<enum>" elements.
14.1.8. Element 13.1.8. Element
The "<enum>" element stores a list of values allowed for storage in The "<enum>" element stores a list of values allowed for storage in
the "EBML Element". The values MUST match the "type" of the "EBML the "EBML Element". The values MUST match the "type" of the "EBML
Element" (for example "<enum value="Yes">" cannot be a valid value Element" (for example "<enum value="Yes">" cannot be a valid value
for a "EBML Element" that is defined as an unsigned integer). An for a "EBML Element" that is defined as an unsigned integer). An
"<enum>" element MAY also store "<documentation>" elements to further "<enum>" element MAY also store "<documentation>" elements to further
describe the "<enum>". describe the "<enum>".
14.1.9. Attributes 13.1.9. Attributes
14.1.9.1. label 13.1.9.1. label
The "label" provides a concise expression for human consumption that The "label" provides a concise expression for human consumption that
describes what the "value" of the "<enum>" represents. describes what the "value" of the "<enum>" represents.
The "label" attribute is OPTIONAL. The "label" attribute is OPTIONAL.
14.1.9.2. value 13.1.9.2. value
The "value" represents data that MAY be stored within the "EBML The "value" represents data that MAY be stored within the "EBML
Element". Element".
The "value" attribute is REQUIRED. The "value" attribute is REQUIRED.
14.1.10. XML Schema for EBML Schema 13.1.10. XML Schema for EBML Schema
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns="https://ietf.org/cellar/ebml" <xsd:schema xmlns="https://ietf.org/cellar/ebml"
targetNamespace="https://ietf.org/cellar/ebml" targetNamespace="https://ietf.org/cellar/ebml"
xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsd="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" version="01"> elementFormDefault="qualified" version="01">
<xsd:element name="EBMLSchema" type="EBMLSchemaType"/> <xsd:element name="EBMLSchema" type="EBMLSchemaType"/>
<xsd:complexType name="EBMLSchemaType"> <xsd:complexType name="EBMLSchemaType">
<xsd:sequence> <xsd:sequence>
<xsd:element name="element" type="elementType" minOccurs="0" <xsd:element name="element" type="elementType" minOccurs="0"
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</xsd:complexType> </xsd:complexType>
<xsd:complexType name="documentationType" mixed="true"> <xsd:complexType name="documentationType" mixed="true">
<xsd:sequence> <xsd:sequence>
<xsd:any namespace="##any" minOccurs="0" maxOccurs="unbounded"/> <xsd:any namespace="##any" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence> </xsd:sequence>
<xsd:attribute name="lang"/> <xsd:attribute name="lang"/>
<xsd:attribute name="type"/> <xsd:attribute name="type"/>
</xsd:complexType> </xsd:complexType>
</xsd:schema> </xsd:schema>
14.1.11. EBML Schema Example 13.1.11. EBML Schema Example
<?xml version="1.0" encoding="utf-8"?> <?xml version="1.0" encoding="utf-8"?>
<EBMLSchema xmlns="https://ietf.org/cellar/ebml" <EBMLSchema xmlns="https://ietf.org/cellar/ebml"
docType="files-in-ebml-demo" version="1"> docType="files-in-ebml-demo" version="1">
<!-- constraints to the range of two EBML Header Elements --> <!-- constraints to the range of two EBML Header Elements -->
<element name="EBMLReadVersion" path="1*1(\EBML\EBMLReadVersion)" <element name="EBMLReadVersion" path="1*1(\EBML\EBMLReadVersion)"
id="0x42F7" minOccurs="1" maxOccurs="1" range="1" default="1" id="0x42F7" minOccurs="1" maxOccurs="1" range="1" default="1"
type="uinteger"/> type="uinteger"/>
<element name="EBMLMaxSizeLength" path="1*1(\EBML\EBMLMaxSizeLength)" <element name="EBMLMaxSizeLength" path="1*1(\EBML\EBMLMaxSizeLength)"
id="0x42F3" minOccurs="1" maxOccurs="1" range="8" default="8" id="0x42F3" minOccurs="1" maxOccurs="1" range="8" default="8"
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</documentation> </documentation>
</element> </element>
<element name="Data" path="1*1(\Files\File\Data)" id="0x4664" <element name="Data" path="1*1(\Files\File\Data)" id="0x4664"
type="binary" minOccurs="1"> type="binary" minOccurs="1">
<documentation lang="en" type="definition"> <documentation lang="en" type="definition">
The data of the file. The data of the file.
</documentation> </documentation>
</element> </element>
</EBMLSchema> </EBMLSchema>
14.1.12. Identically Recurring Elements 13.1.12. Identically Recurring Elements
An "Identically Recurring Element" is an "EBML Element" that MAY An "Identically Recurring Element" is an "EBML Element" that MAY
occur within its "Parent Element" more than once but that each occur within its "Parent Element" more than once but that each
recurrence within that "Parent Element" MUST be identical both in recurrence within that "Parent Element" MUST be identical both in
storage and semantics. "Identically Recurring Elements" are storage and semantics. "Identically Recurring Elements" are
permitted to be stored multiple times within the same "Parent permitted to be stored multiple times within the same "Parent
Element" in order to increase data resilience and optimize the use of Element" in order to increase data resilience and optimize the use of
"EBML" in transmission. For instance a pertinent "Top-Level Element" "EBML" in transmission. For instance a pertinent "Top-Level Element"
could be periodically resent within a data stream so that an "EBML could be periodically resent within a data stream so that an "EBML
Reader" which starts reading the stream from the middle could better Reader" which starts reading the stream from the middle could better
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transmission. If a "Parent Element" contains more than one copy of transmission. If a "Parent Element" contains more than one copy of
an "Identically Recurring Element" which includes a "CRC-32 Element" an "Identically Recurring Element" which includes a "CRC-32 Element"
as a "Child Element" then the first instance of the "Identically as a "Child Element" then the first instance of the "Identically
Recurring Element" with a valid CRC-32 value should be used for Recurring Element" with a valid CRC-32 value should be used for
interpretation. If a "Parent Element" contains more than one copy of interpretation. If a "Parent Element" contains more than one copy of
an "Identically Recurring Element" which does not contain a "CRC-32 an "Identically Recurring Element" which does not contain a "CRC-32
Element" or if "CRC-32 Elements" are present but none are valid then Element" or if "CRC-32 Elements" are present but none are valid then
the first instance of the "Identically Recurring Element" should be the first instance of the "Identically Recurring Element" should be
used for interpretation. used for interpretation.
14.1.13. Expression of range 13.1.13. Expression of range
The "range" attribute MUST only be used with "EBML Elements" that are The "range" attribute MUST only be used with "EBML Elements" that are
either "signed integer", "unsigned integer", "float", or "date". The either "signed integer", "unsigned integer", "float", or "date". The
"range" expression may contain whitespace for readability but "range" expression may contain whitespace for readability but
whitespace within a "range" expression MUST NOT convey meaning. The whitespace within a "range" expression MUST NOT convey meaning. The
expression of the "range" MUST adhere to one of the following forms: expression of the "range" MUST adhere to one of the following forms:
o "x-y" where x and y are integers or floats and "y" MUST be greater o "x-y" where x and y are integers or floats and "y" MUST be greater
than "x", meaning that the value MUST be greater than or equal to than "x", meaning that the value MUST be greater than or equal to
"x" and less than or equal to "y". "x" MUST be less than "y". "x" and less than or equal to "y". "x" MUST be less than "y".
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o "<x" where "x" is an integer or float, meaning that the value MUST o "<x" where "x" is an integer or float, meaning that the value MUST
be less than "x". be less than "x".
o "<=x" where "x" is an integer or float, meaning that the value o "<=x" where "x" is an integer or float, meaning that the value
MUST be less than or equal to "x". MUST be less than or equal to "x".
o "x" where "x" is an integer or float, meaning that the value MUST o "x" where "x" is an integer or float, meaning that the value MUST
be equal "x". be equal "x".
The "range" may use the prefix "not" to indicate that the expressed The "range" may use the prefix "not" to indicate that the expressed
range is negated. Please also see Section 14.1.14. range is negated. Please also see Section 13.1.14.
14.1.14. Textual expression of floats 13.1.14. Textual expression of floats
When a float value is represented textually in an "EBML Schema", such When a float value is represented textually in an "EBML Schema", such
as within a "default" or "range" value, the float values MUST be as within a "default" or "range" value, the float values MUST be
expressed as Hexadecimal Floating-Point Constants as defined in the expressed as Hexadecimal Floating-Point Constants as defined in the
C11 standard [ISO.9899.2011] (see section 6.4.4.2 on Floating C11 standard [ISO.9899.2011] (see section 6.4.4.2 on Floating
Constants). The following table provides examples of expressions of Constants). The following table provides examples of expressions of
float ranges. float ranges.
+-------------------+-----------------------------------------+ +-------------------+-----------------------------------------+
| as decimal | as Hexadecimal Floating-Point Constants | | as decimal | as Hexadecimal Floating-Point Constants |
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maximum value permitted by the range. Hexadecimal Floating-Point maximum value permitted by the range. Hexadecimal Floating-Point
Constants also use a "-" (hyphen) when indicating a negative binary Constants also use a "-" (hyphen) when indicating a negative binary
power. Within a float range, when a "-" (hyphen) is immediately power. Within a float range, when a "-" (hyphen) is immediately
preceded by a letter "p", then the "-" (hyphen) is a part of the preceded by a letter "p", then the "-" (hyphen) is a part of the
Hexadecimal Floating-Point Constant which notes negative binary Hexadecimal Floating-Point Constant which notes negative binary
power. Within a float range, when a "-" (hyphen) is not immediately power. Within a float range, when a "-" (hyphen) is not immediately
preceded by a letter "p", then the "-" (hyphen) represents the preceded by a letter "p", then the "-" (hyphen) represents the
separator between the minimal and maximum value permitted by the separator between the minimal and maximum value permitted by the
range. range.
14.1.15. Note on the use of default attributes to define Mandatory EBML 13.1.15. Note on the use of default attributes to define Mandatory EBML
Elements Elements
If a "Mandatory EBML Element" has a default value declared by an If a "Mandatory EBML Element" has a default value declared by an
"EBML Schema" and the value of the "EBML Element" is equal to the "EBML Schema" and the value of the "EBML Element" is equal to the
declared default value then that "EBML Element" is not required to be declared default value then that "EBML Element" is not required to be
present within the "EBML Document" if its "Parent Element" is present within the "EBML Document" if its "Parent Element" is
present. In this case, the default value of the "Mandatory EBML present. In this case, the default value of the "Mandatory EBML
Element" MUST be interpreted by the "EBML Reader" although the "EBML Element" MUST be interpreted by the "EBML Reader" although the "EBML
Element" is not present within its "Parent Element". Element" is not present within its "Parent Element".
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| declared? | default? | present? | REQUIRED? | | declared? | default? | present? | REQUIRED? |
+---------------+---------------+---------------+-------------------+ +---------------+---------------+---------------+-------------------+
| Yes | Yes | Yes | No | | Yes | Yes | Yes | No |
| Yes | Yes | No | No | | Yes | Yes | No | No |
| Yes | No | Yes | Yes | | Yes | No | Yes | Yes |
| Yes | No | No | No | | Yes | No | No | No |
| No | n/a | Yes | Yes | | No | n/a | Yes | Yes |
| No | n/a | No | No | | No | n/a | No | No |
+---------------+---------------+---------------+-------------------+ +---------------+---------------+---------------+-------------------+
14.2. EBML Header Elements 13.2. EBML Header Elements
This document contains definitions of all "EBML Elements" of the This document contains definitions of all "EBML Elements" of the
"EBML Header". "EBML Header".
14.2.1. EBML Element 13.2.1. EBML Element
name: "EBML" name: "EBML"
path: "1*1(\EBML)" path: "1*1(\EBML)"
id: "0x1A45DFA3" id: "0x1A45DFA3"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
type: "Master Element" type: "Master Element"
description: Set the "EBML" characteristics of the data to follow. description: Set the "EBML" characteristics of the data to follow.
Each "EBML Document" has to start with this. Each "EBML Document" has to start with this.
14.2.2. EBMLVersion Element 13.2.2. EBMLVersion Element
name: "EBMLVersion" name: "EBMLVersion"
path: "1*1(\EBML\EBMLVersion)" path: "1*1(\EBML\EBMLVersion)"
id "0x4286" id "0x4286"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
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range: not 0 range: not 0
default: 1 default: 1
type: Unsigned Integer type: Unsigned Integer
description: The version of "EBML" specifications used to create the description: The version of "EBML" specifications used to create the
"EBML Document". The version of "EBML" defined in this document is "EBML Document". The version of "EBML" defined in this document is
1, so "EBMLVersion" SHOULD be 1. 1, so "EBMLVersion" SHOULD be 1.
14.2.3. EBMLReadVersion Element 13.2.3. EBMLReadVersion Element
name: "EBMLReadVersion" name: "EBMLReadVersion"
path: "1*1(\EBML\EBMLReadVersion)" path: "1*1(\EBML\EBMLReadVersion)"
id: "0x42F7" id: "0x42F7"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
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minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
range: 1 range: 1
default: 1 default: 1
type: Unsigned Integer type: Unsigned Integer
description: The minimum "EBML" version an "EBML Reader" has to description: The minimum "EBML" version an "EBML Reader" has to
support to read this "EBML Document". The "EBMLReadVersion Element" support to read this "EBML Document". The "EBMLReadVersion Element"
MUST be less than or equal to "EBMLVersion". MUST be less than or equal to "EBMLVersion".
14.2.4. EBMLMaxIDLength Element 13.2.4. EBMLMaxIDLength Element
name: "EBMLMaxIDLength" name: "EBMLMaxIDLength"
path: "1*1(\EBML\EBMLMaxIDLength)" path: "1*1(\EBML\EBMLMaxIDLength)"
id "0x42F2" id "0x42F2"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
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default: 4 default: 4
type: Unsigned Integer type: Unsigned Integer
description: The "EBMLMaxIDLength Element" stores the maximum length description: The "EBMLMaxIDLength Element" stores the maximum length
in octets of the "Element IDs" to be found within the "EBML Body". in octets of the "Element IDs" to be found within the "EBML Body".
An "EBMLMaxIDLength Element" value of four is RECOMMENDED, though An "EBMLMaxIDLength Element" value of four is RECOMMENDED, though
larger values are allowed. larger values are allowed.
14.2.5. EBMLMaxSizeLength Element 13.2.5. EBMLMaxSizeLength Element
name: "EBMLMaxSizeLength" name: "EBMLMaxSizeLength"
path: "1*1(\EBML\EBMLMaxSizeLength)" path: "1*1(\EBML\EBMLMaxSizeLength)"
id "0x42F3" id "0x42F3"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
skipping to change at page 34, line 11 skipping to change at page 34, line 33
description: The "EBMLMaxSizeLength Element" stores the maximum description: The "EBMLMaxSizeLength Element" stores the maximum
length in octets of the expression of all "Element Data Sizes" to be length in octets of the expression of all "Element Data Sizes" to be
found within the "EBML Body". To be clear the "EBMLMaxSizeLength found within the "EBML Body". To be clear the "EBMLMaxSizeLength
Element" documents the maximum 'length' of all "Element Data Size" Element" documents the maximum 'length' of all "Element Data Size"
expressions within the "EBML Body" and not the maximum 'value' of all expressions within the "EBML Body" and not the maximum 'value' of all
"Element Data Size" expressions within the "EBML Body". "EBML "Element Data Size" expressions within the "EBML Body". "EBML
Elements" that have an "Element Data Size" expression which is larger Elements" that have an "Element Data Size" expression which is larger
in octets than what is expressed by "EBMLMaxSizeLength ELEMENT" SHALL in octets than what is expressed by "EBMLMaxSizeLength ELEMENT" SHALL
be considered invalid. be considered invalid.
14.2.6. DocType Element 13.2.6. DocType Element
name: "DocType" name: "DocType"
path: "1*1(\EBML\DocType)" path: "1*1(\EBML\DocType)"
id "0x4282" id "0x4282"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
size: >0 size: >0
type: String type: String
description: A string that describes and identifies the content of description: A string that describes and identifies the content of
the "EBML Body" that follows this "EBML Header". the "EBML Body" that follows this "EBML Header".
14.2.7. DocTypeVersion Element 13.2.7. DocTypeVersion Element
name: "DocTypeVersion" name: "DocTypeVersion"
path: "1*1(\EBML\DocTypeVersion)" path: "1*1(\EBML\DocTypeVersion)"
id "0x4287" id "0x4287"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
range: not 0 range: not 0
default: 1 default: 1
type: Unsigned Integer type: Unsigned Integer
description: The version of "DocType" interpreter used to create the description: The version of "DocType" interpreter used to create the
"EBML Document". "EBML Document".
14.2.8. DocTypeReadVersion Element 13.2.8. DocTypeReadVersion Element
name: DocTypeReadVersion name: DocTypeReadVersion
path: "1*1(\EBML\DocTypeReadVersion)" path: "1*1(\EBML\DocTypeReadVersion)"
id "0x4285" id "0x4285"
minOccurs: 1 minOccurs: 1
maxOccurs: 1 maxOccurs: 1
skipping to change at page 35, line 28 skipping to change at page 36, line 5
default: 1 default: 1
type: Unsigned Integer type: Unsigned Integer
description: The minimum "DocType" version an "EBML Reader" has to description: The minimum "DocType" version an "EBML Reader" has to
support to read this "EBML Document". The value of the support to read this "EBML Document". The value of the
"DocTypeReadVersion Element" MUST be less than or equal to the value "DocTypeReadVersion Element" MUST be less than or equal to the value
of the "DocTypeVersion Element". of the "DocTypeVersion Element".
14.3. Global Elements 13.3. Global Elements
EBML defines these "Global Elements" which MAY be stored within any EBML defines these "Global Elements" which MAY be stored within any
"Master Element" of an "EBML Document" as defined by their "Element "Master Element" of an "EBML Document" as defined by their "Element
Path". Path".
14.3.1. CRC-32 Element 13.3.1. CRC-32 Element
name: CRC-32 name: CRC-32
path: "*1((1*\)\CRC-32)" path: "*1((1*\)\CRC-32)"
id: "0xBF" id: "0xBF"
minOccurs: 0 minOccurs: 0
maxOccurs: 1 maxOccurs: 1
skipping to change at page 36, line 13 skipping to change at page 36, line 39
stored except for the "CRC-32 Element" itself. When the "CRC-32 stored except for the "CRC-32 Element" itself. When the "CRC-32
Element" is present, the "CRC-32 Element" MUST be the first ordered Element" is present, the "CRC-32 Element" MUST be the first ordered
"EBML Element" within its "Parent Element" for easier reading. All "EBML Element" within its "Parent Element" for easier reading. All
"Top-Level Elements" of an "EBML Document" that are "Master Elements" "Top-Level Elements" of an "EBML Document" that are "Master Elements"
SHOULD include a "CRC-32 Element" as a "Child Element". The CRC in SHOULD include a "CRC-32 Element" as a "Child Element". The CRC in
use is the IEEE-CRC-32 algorithm as used in the [ISO.3309.1979] use is the IEEE-CRC-32 algorithm as used in the [ISO.3309.1979]
standard and in section 8.1.1.6.2 of [ITU.V42.1994], with initial standard and in section 8.1.1.6.2 of [ITU.V42.1994], with initial
value of "0xFFFFFFFF". The CRC value MUST be computed on a little value of "0xFFFFFFFF". The CRC value MUST be computed on a little
endian bitstream and MUST use little endian storage. endian bitstream and MUST use little endian storage.
14.3.2. Void Element 13.3.2. Void Element
name: Void name: Void
path: "*((*\)\Void)" path: "*((*\)\Void)"
id: "0xEC" id: "0xEC"
minOccurs: 0 minOccurs: 0
type: Binary type: Binary
skipping to change at page 36, line 24 skipping to change at page 37, line 4
name: Void name: Void
path: "*((*\)\Void)" path: "*((*\)\Void)"
id: "0xEC" id: "0xEC"
minOccurs: 0 minOccurs: 0
type: Binary type: Binary
description: Used to void damaged data, to avoid unexpected behaviors description: Used to void damaged data, to avoid unexpected behaviors
when using damaged data. The content is discarded. Also used to when using damaged data. The content is discarded. Also used to
reserve space in a sub-element for later use. reserve space in a sub-element for later use.
15. References 14. Considerations for Reading EBML Data
15.1. Normative References The following scenarios describe events to consider when reading
"EBML Documents" and the recommended design of an "EBML Reader".
If a "Master Element" contains a "CRC-32 Element" that doesn't
validate, then the "EBML Reader" MAY ignore all contained data except
for "Descendant Elements" which contain their own valid "CRC-32
Element".
If a "Master Element" contains more occurrences of a "Child Master
Element" than permitted according to the "maxOccurs" and "recurring"
attributes of the definition of that "Element" then the occurrences
in addition to "maxOccurs" MAY be ignored.
If a "Master Element" contains more occurrences of a "Child Element"
that is not a "Master Element" than permitted according to the
"maxOccurs" attribute of the definition of that "Element" then all
but the instance of that "Element" with the smallest byte offset from
the beginning of its "Parent Element" SHOULD be ignored.
15. IANA Considerations
This document creates a new IANA Registry called "CELLAR EBML Element
ID Registry".
Element IDs are described in section "Element ID". Element IDs are
encoded using the VINT mechanism described in section Section 5 can
be between one and five octets long. Five octet long Element IDs are
possible only if declared in the header.
The VINT Data value of one-octet Element IDs MUST be between 0x01 and
0x7E. These items are valuable because they are short, and need to
be used for commonly repeated elements. Values from 1 to 126 are to
be allocated according to RFC Required.
The VINT Data value of two-octet Element IDs MUST be between 0x007F
and 0x3FFE. Numbers MAY be allocated within this range according to
Specification Required.
The numbers 0x3FFF and 0x4000 are RESERVED.
The VINT Data value of three-octet Element IDs MUST be between 0x4001
and 0x1FFFFE. Numbers may be allocated within this range according
to First Come First Served (see [RFC8126])
The numbers 0x1FFFFF and 0x200000 are RESERVED.
Four octet Element IDs are numbers between 0x2000001 and 0xFFFFFFE.
Four octet Element IDs are somewhat special in that they are useful
for resynchronizing to major structures in the event of data
corruption or loss. As such four octet Element IDs are split into
two categories. Four octet Element IDs whose lower three octets (as
encoded) would make printable 7-bit ASCII values may be allocated
only Specification Required. Sequential allocation of values is not
required: specifications SHOULD include a specific request, and are
encouraged to do early allocations.
To be clear about the above category: four octet Element IDs always
start with hex 0x10 to 0x1F, and that octet may be chosen so that the
entire number has some desirable property, such as a specific CRC.
The other three octets, when ALL having values between 0x21 (33,
ASCII !) and 0x7e (126, ASCII ~), fall into this catgory.
Other four octet Element IDs may be allocated by First Come First
Served (see [RFC8126]).
The numbers 0xFFFFFFF and 0x1000000 are RESERVED.
Five octet Element IDs (values from 0x10000001 upwards) are reserved
for Experimental use: they may be used by anyone at any time, but
there is no coordination.
16. References
16.1. Normative References
[IEEE.754.1985] [IEEE.754.1985]
Institute of Electrical and Electronics Engineers, Institute of Electrical and Electronics Engineers,
"Standard for Binary Floating-Point Arithmetic", "Standard for Binary Floating-Point Arithmetic",
IEEE Standard 754, August 1985. IEEE Standard 754, August 1985.
[ISO.3309.1979] [ISO.3309.1979]
International Organization for Standardization, "Data International Organization for Standardization, "Data
communication - High-level data link control procedures - communication - High-level data link control procedures -
Frame structure", ISO Standard 3309, 1979. Frame structure", ISO Standard 3309, 1979.
skipping to change at page 37, line 35 skipping to change at page 39, line 40
<https://www.rfc-editor.org/info/rfc5234>. <https://www.rfc-editor.org/info/rfc5234>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying [RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <https://www.rfc-editor.org/info/rfc5646>. September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF", [RFC7405] Kyzivat, P., "Case-Sensitive String Support in ABNF",
RFC 7405, DOI 10.17487/RFC7405, December 2014, RFC 7405, DOI 10.17487/RFC7405, December 2014,
<https://www.rfc-editor.org/info/rfc7405>. <https://www.rfc-editor.org/info/rfc7405>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[W3C.REC-xml-20081126] [W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", World Wide Web Consortium Recommendation REC- Edition)", World Wide Web Consortium Recommendation REC-
xml-20081126, November 2008, xml-20081126, November 2008,
<http://www.w3.org/TR/2008/REC-xml-20081126>. <http://www.w3.org/TR/2008/REC-xml-20081126>.
15.2. Informative References 16.2. Informative References
[W3C.REC-xmlschema-0-20010502] [W3C.REC-xmlschema-0-20010502]
Fallside, D., "XML Schema Part 0: Primer", World Wide Web Fallside, D., "XML Schema Part 0: Primer", World Wide Web
Consortium Recommendation REC-xmlschema-0-20010502, May Consortium Recommendation REC-xmlschema-0-20010502, May
2001, 2001,
<http://www.w3.org/TR/2001/REC-xmlschema-0-20010502>. <http://www.w3.org/TR/2001/REC-xmlschema-0-20010502>.
Authors' Addresses Authors' Addresses
Steve Lhomme Steve Lhomme
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