It is intended to make the length of the arrays in aiAnimMesh accessible even if the associated aiMesh is not known, e.g. in language bindings. Once the data structure is actually used inside Assimp, it could be set for all aiAnimMeshes from aiMesh::NumVertices in the Assimp::Importer after everything else has been completed.
git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@768 67173fc5-114c-0410-ac8e-9d2fd5bffc1f