Don't worry VinnyD, it happens to all of us.
hussein

What about a name like Abu Mazen? I am under the impression that this is something like a nom de guerre and there are several others like it.

That's probably just a kunya based on the name of his firstborn son. It seems to have been a Fatah practice to use a kunya as a nom de guerre, either one based on the name of your son or invented, like Abu Ammar (Yasser Arafat -- Ammar ibn Yasser was a companion of the Prophet) or Abu Jihad.
(I checked on Ammar ibn Yasser, which I had first written as Yasser ibn Ammar. No more relying on memory!)