@margaret, @davidgolber - I am not sure - Help has this:
The pull direction for DraftAngleAnalysis is the z-axis of the construction plane that is in the active viewport when the command starts.
The normal direction of the surface is the same as the pull direction of the mold. You can check this with the Dir command.
Changing the construction plane before using DraftAngleAnalysis lets you define any direction as the pull direction.
We could re-word that perhaps:
The normal direction of a the object ( Dir command, Analyze menu > Direction) should correspond to the side of the mold that will be pulled from it.
??
-Pascal