Premultiplication And Alpha

All images and clips have a premultiplication state. This is used to indicate how the image should interpret RGB (or YUV) pixels, with respect to alpha. The premultiplication state can be...

This document won't go into the details of premultiplication, but will simply state that OFX takes notice of it and flags images and clips accordingly.

The premultiplication state of a clip is constant over the entire duration of that clip.