The weapon proficiency list file is to set what each weapon category a weapon belongs to (Simple, Martial, Exotic, Natural) so that PCGen can determine whether or not a character qualifies to use that weapon or not. The 1st field is the name filed, there is no tag for it, just the name of the weapon proficiency.
Tag Name: TYPE
Variable(s) Used: Text
Example(s): TYPE:SIMPLE
Example(s): TYPE:MARTIAL
Example(s): TYPE:EXOTIC
Example(s): TYPE:NATURAL
WHAT IT DOES: This defines for PCGen what type of weapon proficiency it is for characters to be able to use the weapon
Tag Name: SIZE
Variable(s) Used: Text (F,D,T,S,M,L,H,G,C)
Example(s): SIZE:M
WHAT IT DOES: This determines if the weapon is light, one-handed or two-handed for the character's race
Tag Name: HANDS
Variable(s) Used: Numeric
Example(s): HANDS:2
WHAT IT DOES: The minimum number of hands required to use the weapon. Defaults to a value of 1