This repository hosts material that accompanies the USD Core Specification, developed by the Alliance for OpenUSD (AOUSD): sample implementations of spec-defined behavior, and the framework used to assess compliance with the specification.
The sample implementations are reference quality. They are intended to illustrate the specification, not to serve as a normative or production-grade implementation. The USD Core Specification itself is the normative reference. The exact set of components included in any given release is listed in that release's own README.
| Release | Released | Pairs with Core Spec | Source |
|---|---|---|---|
1.0.1.post0 |
2025-12-18 | v1.0.1 | releases/1.0.1/ |
Each release is a self-contained Python package. To run a release in place:
cd releases/<version>
uv run -m unittest discover
Releases follow PEP 440 using the
form <core-spec-version>.post<N>. For example, 1.0.1.post0 is the
first supplemental release tested against the USD Core Specification
v1.0.1; 1.0.1.post1 would be a subsequent supplemental release still
paired with v1.0.1.
This scheme keeps the pairing visible in the version string while allowing supplemental releases to ship on a cadence independent of the USD Core Specification.
The directory hierarchy uses the USD Core Specification version
(releases/1.0.1/) and may host multiple post-releases over time
(reflected in tags) without renaming. Tags use the full PEP 440
version including the post-release suffix
(release/1.0.1.post0).
The USD Core Specification defines the foundational data model, composition semantics, file formats, and schemas of Universal Scene Description (USD). It is published at aousd.org.
The normative specification artifacts are also available in
the aousd/specifications-public
repository.
For more about AOUSD and its working groups, see https://aousd.org.
We welcome bug reports, reports of divergence from the USD Core Specification or from upstream OpenUSD behavior, and pull requests that extend test coverage or improve the compliance-testing framework. Please file these in this repository's issue tracker or open a pull request.
For questions or general discussion about the USD Core Specification itself, please post on the AOUSD forum at forum.aousd.org.
The sample implementations follow the USD Core Specification rather than leading it: changes to the behavior they model are introduced through the specification's own process and then reflected here.
The supplemental material in this repository is published under the Apache License 2.0.