COLLADA defines an XML Namespace and database schema to make it easy to transport 3D assets between applications without loss of information, enabling diverse 3D authoring and processing tools to be combined into a content production pipeline.
More readable than you might expect. See precisely which elements are allowed where.
curl -L http://www.khronos.org/files/collada_schema_1_5 > collada_schema_1_5.xsd
Based on lxml and numpy, so should be fast enough.