[Technical] The LS states that “ISO/IEC DIS 23090-39 does not yet specify compression mechanisms,” but does not distinguish between normative bitstream compression vs transport-level compression; this ambiguity weakens the question and may lead to an unhelpful response from ISO/IEC.

[Technical] The request asks generally for “existing MPEG technologies” for mesh and animation compression, but does not constrain the scope to technologies compatible with ARF’s data model (e.g., topology changes, blendshape representation, skeleton hierarchy), so ISO/IEC cannot assess feasibility of integration into 23090-39.

[Technical] The LS does not clarify whether SA4 needs a standardized codec/bitstream (e.g., normative decoding) or merely recommended encodings; this is critical because MPEG technologies differ substantially in standardization maturity and integration burden.

[Technical] “Avatar animation data including blend shape sets, skeletal animation, other animation-related information” is underspecified: it omits key elements such as skinning weights, joint constraints, time sampling, quantization requirements, and coordinate systems, which directly affect compressibility and choice of technology.

[Technical] The LS does not mention whether compression must support random access, streaming, incremental updates, and partial avatar updates (common in IMS conversational scenarios); without these requirements, ISO/IEC cannot map to appropriate MPEG tools.

[Technical] The timeline presented (study conclusion Aug 2026; normative work Mar 2027) is inconsistent with typical 3GPP Release 20 planning and may be interpreted as non-actionable by ISO/IEC; the LS should align to the actual Rel-20/Rel-21 milestone framework or explicitly state it is SA4 internal planning.

[Technical] The document claims adoption of “ISO/IEC DIS 23090-39” in Rel-19 TS 26.264; referencing a DIS (draft) rather than the final ISO/IEC publication is risky and should be clarified (which edition/stage is normatively referenced in TS 26.264).

[Technical] The LS does not identify the exact clauses in TS 26.264 impacted by adding compression (e.g., payload formats, SDP signaling, file/stream encapsulation), so ISO/IEC cannot gauge what “integration into 23090-39” would need to cover for 3GPP interoperability.

[Technical] Asking WG7 and WG3 jointly is plausible, but the LS does not justify which group is expected to answer which aspect (ARF vs compression tools), increasing the chance of diffusion of responsibility and delayed response.

[Editorial] The LS reads like an internal summary rather than a formal liaison: it lacks typical LS elements (explicit addressee, LS purpose, contact points, meeting reference, and a clear “Action requested by” date tied to SA4 milestones).

[Editorial] The term “avatar communication Phase 2” is used without referencing the corresponding 3GPP work item/study item identifier, making it harder for ISO/IEC to trace scope and urgency.

[Editorial] The wording “considering the Release 20 timeline constraints” is vague; the LS should state the latest date by which SA4 needs an answer (e.g., before a specific SA4 meeting) to be actionable.