Material Function Assignment Enumeration

Member name	Value	Description
None	0	Priority = 0 This is deprecated and should not be used.
Structure	1	Priority = 1 (highest priority)
Substrate	2	Priority = 2
Insulation	3	Priority = 3
Finish1	4	Priority = 4
Finish2	5	Priority = 5
Membrane	100	A membrane layer must have thickness 0. It is not represented graphically.
StructuralDeck	200	Indicates layer is a structural deck.

The function is used primarily to determine layer priority which affects how layers of distinct elements interact at a join. Typically, layers penetrate lower priority layers and merge with layers of the same priority.

Reference