The Std Substitutes tab is used to identify all alternate parts (substitutes) that can be applied where shortages exist for the selected component/material part. These substitutes are application sensitive and not universal.
If a Copper washer of the same size is specified as an alternate for a Steel washer, the alternate Copper washer would thus only be valid as a substitute when the selected parent part is manufactured.
During manufacturing, the Part Substitutes function must be applied to change the requirements on an order from the original part to an alternate part.
Also see Project Substitutes.