Adding subcategory to Master Material List

[MarkMc]

I can add a subcategory to an item in the material list. I don't see how to add it to all items in a category-IOW to the Master list. I tried update to Master but that doesn't appear to do it. Tried hlep, ref manual, searched here, knowledge base, and scrambled around the rabbit hole for a while.... Am I missing something?

And or is there some way to get "room name" into the material list?

[GerryT]

If the object in the material list is referencing a room: in any category field:  Select 'Apply to same source' then in the field or the common field (top level) enter - =name  as the macro method (= must be first char.) The line item must be referencing the correct object i. e can't use a cabinet line for a room object.