I am mostly thinking about decals such as signs, logos, graffiti and so on.
At present, if I want to have a decal in two different sizes, I have to define two different decals in DECALDEF, If (as I have) I want 4 different sizes, that's 4 definitions of basically the same decal, except the scale parameters. Then, if it's a series of warning signs, or similar, that's multiple copies of multiple signs. It soon gets very busy.
Then there are always the occasions where you have, say, a decal scaled so that it is 32 units wide, and a 64 units one, but when you come to a specific map, what you really need is a 48 unit wide decal. So, it's out of UDB, into the text editor, create a new definition, back into UDB, and only then to realise that 44 was actually better - rinse and repeat until you get something that you want.
The decal thing has several unused arguments. Perhaps one of those could be a scale parameter? Maybe another could be something like translucency? Or maybe the ability to scale a thing (in UDMF) could somehow be used? Obviously I know that the decal thing is not the decal, so I realise that it might not be straight forward. However, if the parameters could somehow be transferred to the properties of the decal that gets spawned, it could be very handy.
