JPN,
Welcome to ac-talk with your first post...which is to the wrong forum. This is a wish forum (with poll) and you are asking a question that belongs in the Libraries / Lib Parts / GDL forum. I'm asking the moderator to move this thread there.
Second, always do a search before posting - 90% of all questions asked have already been answered. This is not to discourage posts - only to save everyone's time, including the person with the question who then gets an immediate answer.
Searching on the words 'material label' gives this result:
http://archicad-talk.graphisoft.com/viewtopic.php?p=4102#4102
which I believe is what you are looking for?
In the GDL Reference Manual you will find:
REQUEST ("Name_of_material", index, name)
Returns in the variable the material name identified by index.
Cheers,
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB