Read and write generated coordinates (also known as "original coordinates", "reference coordinates", or "orcos") from and to Alembic. A custom geometry property named "Pref" is used for (hopefully) interoperability with Maya and Houdini. For now it's only guaranteed for Blender-to-Blender. Export: writing generated coordinates is optional (on by default). Import: generated coordinates are always read whenever the reading of vertex data is enabled. Manifest Task: T88081