I am the assigned Gen-ART reviewer for this draft. The General Area Review Team (Gen-ART) reviews all IETF documents being processed by the IESG for the IETF Chair. Please treat these comments just like any other last call comments. For more information, please see the FAQ at . Document: draft-ietf-cellar-codec-?? Reviewer: Mallory Knodel Review Date: 2026-06-01 IETF LC End Date: 2026-05-29 IESG Telechat date: Not scheduled for a telechat Summary: This document describes how to map codecs into the Matroska container format. The draft is well written and clear in purpose. Major issues: None. Thanks for the document. The biggest challenge I faced while reviewing this was to do my best to check out all of the different reference documents (there are so many! and from many other standards bodies). I guess that this is the core function of this work, to bring together many different codecs into one standard framework. Caveat that this is a general review and not a technical review. Minor issues: * Decide whether codec is plural and if so delete all "codecs" (love an invariable noun). * There is confusion for a new reader between "Block Addition" and "Block Additional", both a kind of necessary mapping. What seems to be the difference is that the latter is about mapping additional /data/, not about adding a block of data. That's a nuance. It would be helpful to define this in an introductory paragraph. This sort of introductory paragraph can also provide a guide to the table of contents-- why there are mappings of codecs and blocks, both for audio and video, and how to handle the data within them. That high-level architectural explanation is missing from the doc. If it exists elsewhere, you could link to that and summarize. Nits/editorial comments: * Also on the plural tack: You could probably say "Codec Mapping" rather than the plural form in most cases, just for consistency, and for the title of section 3 specifically, but not, say, 3.2. or 3.3.. * 3.3.1: "doesn't contains"