VTA
From Valve Developer Community
This article is a stub. You can help by adding to it (http://developer.valvesoftware.com/w/index.php?title=VTA&action=edit).
A VTA or VerTex Animation file (sic!) contains a indexed list of vertices and defines their position and normals per frame. The file's main use is for facial animation and usually contains the changes in vertex positions from the reference for individual shape keys.
File extension is .vta.
