Standard Ptex keys are documented in the following table.
|PtexFaceVertCounts||int32||Number of vertices for each face.||one value per face|
|PtexFaceVertIndices||int32||Index of each face vert within PtexVertPositions array.||one value per vertex per face|
|PtexVertPositions||float||3d position of each vertex.||three values per vertex|
The PtexFaceVertCounts, PtexFaceVertIndices, and PtexVertPositions can be used to describe geometry on which the Ptex texture can be mapped. This data isn't used directly by the Ptex library but can be used by 3d painting programs, Ptex texture viewers, or similar applications.