My grandpa is an engineer so if I get you right, this term is usually used to refer to the number of changes made to a drawing.
This term is commonly used when discussing updates or revisions to drawings or designs.
If you can see the pic I attached here, you may understand it better: If the drawing has been modified in one location, then 处数 should be 1.


If the term appears in a table and there's limited space, you may consider using abbreviation like "Chg. Loc. No."