Scripting?

What scripting does this support?
Does it support DECORATE?
Also, can someone explain Eternity Definition Files?

skib said:

What scripting does this support?

ACS.

Though not ZDoom's ACS, so you've gotta remain within vanilla Hexen features.

Historically there was FraggleScript, but it has been entirely removed a long while ago. Then there is Small, but it is going to go the way of FraggleScript (because of compatibility issues with 64-bit builds) so I wouldn't advise using it.

skib said:

Does it support DECORATE?

No. DECORATE is ZDoom's content definition language, and the only port that supports it that isn't directly derived from ZDoom is Vavoom.

skib said:

Also, can someone explain Eternity Definition Files?

They're Eternity's content definition language. They can do certain things that DECORATE can't; and they can't do certain things that DECORATE can. There's documentation about them on the Eternity wiki.