[transition] CR Snapshot Update Request for Portable Network Graphics (PNG) Specification (Third Edition) - png-3

CR Snapshot Update Request for Portable Network Graphics (PNG) Specification (Third Edition) - png-3
from https://github.com/w3c/transitions/issues/697

# Document URLs
 - https://w3c.github.io/png/

# Link to group's decision to request transition
 - https://github.com/w3c/png/issues/503

# Link to previous Candidate Recommendation transition or update request
 - https://github.com/w3c/transitions/issues/566

# Substantive changes
 - One substantive change (renamed two metadata chunks as unsafe to copy) now adopted by all implementers
 - [Editorial changes since CR Draft of 21 Jan 2025](https://w3c.github.io/png/#changes-20250121/)

# Any changes in requirements?
None

# Wide Review of substantive changes
 - https://github.com/w3c/png/issues/228
 - [Explainer](https://github.com/w3c/png/blob/main/Third_Edition_Explainer.md) used for TAG review
 - Some original PNG specification authors contributing, including becoming IE
 - [libpng](https://github.com/pnggroup/libpng) has shipped support for Third Edition chunks; increased collaboration with PNG WG
 - pnggroup officially adopted [pngcheck](https://github.com/pnggroup/pngcheck)
 - working with [ISO TC 42](https://www.iso.org/committee/48420.html)/WG 23, [Class C liaison](https://www.w3.org/liaisons/#I) in progress
 - Referenced by forthcoming ISO 21496-1 which wants to see it as W3C Recommendation asap
 - Liaison with SMPTE resulted in several SMPTE specifications, normatively referenced by PNG, becoming freely available at our request
 - [libspng](https://libspng.org/) is waiting for 3rd Edition to become a W3C Recommendation before adding support

# Issues status
 - [PNG 3rd Edition issues](https://github.com/w3c/png/issues?q=is%3Aissue%20state%3Aopen%20milestone%3A%223rd%20edition%22)

# Formal Objections
None

# Any changes in implementation information?
**Very** widely implemented - [Implementation Report](https://w3c.github.io/png/Implementation_Report_3e/)

# Deadline for further comments
60 days

# Any changes in patent disclosures?
None

See [Requirements for updating a Candidate Recommendation Snapshot](https://www.w3.org/Guide/transitions?profile=CR&cr=snapshot) for further information.



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Received on Monday, 3 March 2025 22:05:01 UTC