I don't know if this is intended or not (but it doesn't say it is), mobs will simply walk away in the middle of combat if they have the running flag. I don't think it should be possible to just leave a fight by walking southwest, yet it may be intended by the flag (even though it doesn't say).

Thoughts?

Sounds like it should have a isfighting type check in there.

#define ACT_RUNNING		 16   /* Hunts quickly  */

That's pretty much the only explanation of the ACT_RUNNING flag I can find.

In update.c, if this flag is set, the mob will not track people even if it's ch->hunting member has been set to something.
It will not process spec_funs if this flag has been set, even if it has one.
It will engage in normal wandering behavior if the flag is *NOT* set.

Then there is a whole other block in char_check that seems to throw most of that logic right out the window. So in the end I'm not sure what this flag's real purpose is supposed to be, but it doesn't seem to be very useful. Which might explain why I killed it in AFKMud and never missed it.

It might be one of those things they wanted to develop but never really did. I'd say if you can't think of a time you've set it, or if you have no idea why you'd set it, you may as well get rid of it.

The helpfile says "Mobile is running (moves twice as fast)", so this seems to be completely wrong?

Yes, I'd say the helpfile is bogus too. In my mind that leaves the usefulness of the flag in doubt. Which I'm sure is why I got rid of it. I doubt if it disappeared anyone would know the difference.