Matroska Media Container Format Specifications
draft-ietf-cellar-matroska-21

# Internet AD comments for draft-ietf-cellar-matroska-16
CC @ekline

comment syntax: https://github.com/mnot/ietf-comments/blob/main/format.md

## Nits

### S4.4

* s/comprised of/comprising/

  or

  s/comprised of/composed of/

Thanks for your work on this document, and I apologize for the length of time it's taken me to review the changes. I have a couple of final comments. 

1. Thanks for the "Updates to RFC 8794" section! I think you also should add the "Updates" header. I expect this was just an oversight since you've gotten the rest of the formalities right including mentioning the update in the abstract. 

2. I notice you haven't changed the language of the form "are set to 00". I think you asked me about this in an email reply a long time ago and I dropped the ball. Indeed, my suggestion was to use "0b00" instead of "00" (and similar, wherever you are writing out binary, whatever the specific values). That is, I think you should do as other RFCs do and follow the usual C syntax for number representation. As you've written it, with a leading zero and no base indicator, the casual reader might suppose you were using octal, same for "set to 01". Similarly, "are set to 11" looks to my eye as if it meant "are set to (decimal) eleven". Of course, with just a tiny bit of effort, your true meaning can be inferred from "the bits 5-6..." but why not specify the radix?

thanks for addressing and/or explaining the issues I raised.

I have updated my position to No Objection

Thank you for documenting this important format in the IETF.

Thanks for addressing my DISCUSS and COMMENT feedback.

I am balloting "NoObj" in the "I read the protocol action, and this is outside my area of expertise" sense of the term.

I read much of the document, but ¯\_(ツ)_/¯.

Thanks for addressing my discuss points. 

Copying the discuss points below -
======================================================================================================================
However, I have two observation/questions that I would like to discuss to have clear opinions and better understanding.

    - Top-Level Elements are optional fields in the segment. While segment is a MUST part in the container but segments values (elements) are MAY, this to me says one can just put a dummy segment in the container and it will be fine. is that correct interpretation? however, there is a RECOMMENDED segment element, so how should we interpret the statement that Top-level Elements are all MAY?  

    - Even if the Top-Level Elements MAY be available in the container, some of the elements has MUST parts when they are present. However, I have not notices description of the consequences or error handling is those MUST parts are not available in the elements. I wonder what would be the course of action if the MUST parts of a certain element is not there. In general, I was expecting error handling in this specification which is not there and would like to discuss the reasoning behind it.

I like Warren am balloting no objection on the basis that this is way outside of my area of expertise.  I did read 80% of the document though!

# GEN AD review of draft-ietf-cellar-matroska-16

CC @larseggert

Thanks to Elwyn Davies for the General Area Review Team (Gen-ART) review
(https://mailarchive.ietf.org/arch/msg/gen-art/l2gsKdSbRBtCBNMrVZBmmRiu1IM).

## Comments

### Note to self

Check whether Expert Review is an appropriate registration policy here.

### DOWNREFs

Possible DOWNREF from this Standards Track doc to `[Twofish]`. If so, the IESG
needs to approve it.

Possible DOWNREF from this Standards Track doc to `[Blowfish]`. If so, the IESG
needs to approve it.

### Inclusive language

Found terminology that should be reviewed for inclusivity; see
https://www.rfc-editor.org/part2/#inclusive_language for background and more
guidance:

 * Terms `mastertrackuid`, `masteringmetadata`, `mastering`,
   `mastertrackseguid`, and `master`; alternatives might be `active`,
   `central`, `initiator`, `leader`, `main`, `orchestrator`, `parent`,
   `primary`, `server`
 * Term `native`; alternatives might be `built-in`, `fundamental`, `ingrained`,
   `intrinsic`, `original`
 * Term `blindly`; alternatives might be `visually impaired`, `unmindful of`,
   `unconcerned about`, `negligent of`, `unaware`, `uncomprehending`,
   `unaware`, `uncritical`, `unthinking`, `hasty`, `blocked`, `opaque`

## Nits

All comments below are about very minor potential issues that you may choose to
address in some way - or ignore - as you see fit. Some were flagged by
automated tools (via https://github.com/larseggert/ietf-reviewtool), so there
will likely be some false positives. There is no need to let me know what you
did with these suggestions.

### Duplicate references

Duplicate normative references to:
`https://csrc.nist.gov/publications/detail/fips/197/final`.

### Outdated references

Document references `draft-ietf-cellar-tags-09`, but `-10` is the latest
available revision.

Document references `draft-ietf-cellar-codec-09`, but `-10` is the latest
available revision.

### URLs

These URLs in the document can probably be converted to HTTPS:

 * http://web.archive.org/web/20110214132246/http://labs.divx.com/node/16602
 * http://web.archive.org/web/20101222001148/http://labs.divx.com/node/16601
 * http://web.archive.org/web/20160609214806/https://www.fourcc.org/yuv.php
 * http://web.archive.org/web/20160609214806/https://www.fourcc.org/rgb.php

### Grammar/style

#### Section 3, paragraph 3
```
ch should have been used instead. Therefore Matroska writers MUST NOT use EBM
                                  ^^^^^^^^^
```
A comma may be missing after the conjunctive/linking adverb "Therefore".

#### Section 4.4, paragraph 33
```
--------+ Figure 9: Representation of a Attachments Element. The Tags Element
                                      ^
```
Use "an" instead of "a" if the following word starts with a vowel sound, e.g.
"an article", "an hour".

#### Section 5.1.4.1.29.2, paragraph 3
```
s this is the ID of the public key the the data was encrypted with. stream c
                                   ^^^^^^^
```
Possible typo: you repeated a word.

#### Section 5.1.4.1.31.6, paragraph 5
```
g ID to identify the Chapter. For example it is used as the storage for [Web
                                  ^^^^^^^
```
A comma is probably missing here.

#### Section 5.1.7.1.4.11, paragraph 1
```
SHOULD include a CRC-32 Element as a their first Child Element. The Segment
                                   ^^^^^^^
```
A determiner cannot be combined with a possessive pronoun. Did you mean simply
"a" or "their"?

#### Section 5.1.8.1.1.3, paragraph 1
```
yframe flag and Discardable flag. Otherwise everything is the same. Bit 0 is
                                  ^^^^^^^^^
```
A comma may be missing after the conjunctive/linking adverb "Otherwise".

#### Section 6, paragraph 1
```
er flags are set to 00. The Block for a 800 octets frame is as follows: +====
                                      ^
```
Use "an" instead of "a" if the following word starts with a vowel sound, e.g.
"an article", "an hour".

#### Section 10.4.2, paragraph 8
```
multiplied Block Timestamp is a floating values in nanoseconds. The Matroska
                              ^^^^^^^^^^^^^^^^^
```
The plural noun "values" cannot be used with the article "a". Did you mean "a
floating value"?

#### Section 10.4.2, paragraph 8
```
-2 form [ISO639-2] (like "fre" for french), or such a language code followed
                                   ^^^^^^
```
"French" needs to be capitalized when you are referring to the language or
country.

#### Section 10.4.4, paragraph 1
```
 image SHOULD be presented with a 90 degree counter-clockwise rotation, with
                                  ^^^^^^^^^
```
When "90-degree" is used as a modifier, it is usually spelled with a hyphen.

#### Section 11.1.1, paragraph 3
```
ding to the cumulative duration of the the previous Ordered Chapters. As an
                                   ^^^^^^^
```
Possible typo: you repeated a word.

#### Section 11.3, paragraph 2
```
ack with a UID and all its flags. However the codec ID is meaningless becaus
                                  ^^^^^^^
```
A comma may be missing after the conjunctive/linking adverb "However".

#### Section 12, paragraph 2
```
red in the same channel as the track its linked to. When content is found in
                                     ^^^
```
Did you mean "it's" (contraction of "it is/has")?

#### Section 16.2, paragraph 2
```
during the film, which is an unusual specialized audio service that Matroska
                             ^^^^^^^^^^^^^^^^^^^
```
Make sure that the adjective "unusual" is correct. Possibly, it should be an
adverb (typically ~ly) that modifies "specialized". Possibly, it should be the
first word in a compound adjective (hyphenated adjective). Possibly, it is
correct.

#### Section 17, paragraph 1
```
udio tracks and finds that multiple seem equally and maximally preferable, i
                                    ^^^^
```
The verb "seem" is plural. Did you mean: "seems"? Did you use a verb instead of
a noun?

#### Section 17.2.1, paragraph 2
```
 only found in ordered chapters Furthermore there are other EBML Elements wh
                                ^^^^^^^^^^^
```
A comma may be missing after the conjunctive/linking adverb "Furthermore".

#### Section 18.8, paragraph 2
```
 ChapterFlagHidden flag works independently from parent chapters. A Nested Ch
                              ^^^^^^^^^^^^^^^^^^
```
The usual collocation for "independently" is "of", not "from". Did you mean
"independently of"?

#### Section 19.2, paragraph 9
```
d.(jpg|png). The filenames are case sensitive. The following table provides
                               ^^^^^^^^^^^^^^
```
This word is normally spelled with a hyphen.

#### Section 20.1.2, paragraph 1
```
on. This Font Name can be different than the Attachment's FileName, even when
                                    ^^^^
```
Did you mean "different from"? "Different than" is often considered colloquial
style.

#### Section 20.1.2, paragraph 6
```
nts were used in existing files. Therefore it is RECOMMENDED for a Matroska
                                 ^^^^^^^^^
```
A comma may be missing after the conjunctive/linking adverb "Therefore".

#### Section 20.1.3, paragraph 1
```
e file extension check MUST be case insensitive. Matroska writers SHOULD use
                               ^^^^^^^^^^^^^^^^
```
This word is normally spelled with a hyphen.

#### Section 20.2.2, paragraph 3
```
e stream has neither a SeekHead list or a Cues list at the beginning of the
                                     ^^
```
Use "nor" with neither.

#### Section 20.3, paragraph 2
```
s Void Element should be adjusted depending whether the Matroska file already
                                  ^^^^^^^^^
```
The verb "depend" requires the preposition "on" (or "upon").

#### Section 20.4, paragraph 2
```
fore all the locations are known. Therefore shis layout is rarely used. * Se
                                  ^^^^^^^^^
```
A comma may be missing after the conjunctive/linking adverb "Therefore".
Also, shis -> this?

#### Section 20.4, paragraph 2
```
a Reader could include: * Storage of a arbitrary and potentially executable d
                                     ^
```
Use "an" instead of "a" if the following word starts with a vowel sound, e.g.
"an article", "an hour".

#### Section 20.5.1, paragraph 3
```
be allocated according to the "First Come First Served" policy [RFC8126]. The
                                     ^^^^
```
It seems that a comma is missing.

#### Section 27.1, paragraph 12
```
be allocated according to the "First Come First Served" policy [RFC8126]. Cha
                                     ^^^^
```
It seems that a comma is missing.

#### Section 27.1, paragraph 12
```
erTrackUID and MasterTrackSegUID should must be present and BlockGroups for t
                                 ^^^^^^^^^^^
```
Two modal verbs in a row. Did you mean: "should, must", "should" or "must"?

## Notes

This review is in the ["IETF Comments" Markdown format][ICMF], You can use the
[`ietf-comments` tool][ICT] to automatically convert this review into
individual GitHub issues. Review generated by the [`ietf-reviewtool`][IRT].

[ICMF]: https://github.com/mnot/ietf-comments/blob/main/format.md
[ICT]: https://github.com/mnot/ietf-comments
[IRT]: https://github.com/larseggert/ietf-reviewtool