From original 4c RAWs
[CREATURE:ANIMAL_EXOTIC]
[NAME:tough:tough:tough]
[USE_MATERIAL_TEMPLATE:SKIN:TOUGHSKIN_TEMPLATE
[USE_MATERIAL_TEMPLATE:LEATHER:TOUGHLEATHER_TEMPLATE] <-- dual entries for :LEATHER: confuses the game and it only uses one of them,
[USE_MATERIAL_TEMPLATE:LEATHER:LEATHER_EXOTIC] <-- but they had the same properties, if I recall correctly.
[USE_MATERIAL_TEMPLATE:LEATHER_EXOTIC:LEATHER_EXOTIC]
[USE_MATERIAL_TEMPLATE:CHITIN:CHITIN_TEMPLATE]
I made every type of leather (except suede) into it's own fake creature so that they are easier to find when using workflow. Before my changes, you would queue up a leather armor, hit Alt-A to see reagents, hit m to specify the material, hit C to go to the creatures sub menu, and then you would need to locate the blank entry for ANIMAL. You could easily locate "tough" but it would have two leather entries in it. Of course, you had already done this for some of the leathers like studded and lamellar.
By putting all of the leathers into their own fake creature with no name value and only one material, that material becomes the default and no longer resides under a creature. So searching for "rigid chitinplate" is as simple as typing it instead of having to locate the blank named ANIMAL.
I stuck with using the LEATHER_EXOTIC because it was already in use and would make more sense, imo, to match up with all of the [REACTION_CLASS:LEATHER_EXOTIC] tokens used.
And I don't really know if I'm answering you correctly.