The action name limit is 19 chars. You can see in the $$M file if you defined a simple entity - it's a lot shorter and simpler and has only 8 skills and 20 bytes for names - that's why you have the 19 chars limit.

WED always places a simple entity when a normal entity is not needed, f.i. when you don't use more than 8 skills, no material, etc. The simple entity definition starts with the number "3", like this:
Code:
{ //model
	3
	0 0 0
	360 0 0
	0.5 0.5 0.5
	Kugel.mdl
	Model
	A_Modell
	0 0 0 0 0 0 0 0
	0000
	0
}