Detailed Description

Bitmask values for 'can_apply_object()' return values. the CAN_APPLY_ prefix is to just note what function the are returned from.

CAN_APPLY_NEVER: who will never be able to use this - requires a body location who doesn't have.
CAN_APPLY_RESTRICTION: There is some restriction from using this item - this basically means one of the FLAGS are set saying you can't use this.
CAN_APPLY_NOT_MASK - this can be used to check the return value to see if this object can do anything to use this object. If the value returned from can_apply_object() anded with the mask is non zero, then it is out of the control of this creature to use the item. otherwise it means that by unequipping stuff, they could apply the object
CAN_APPLY_UNAPPLY: Player needs to unapply something before applying this.
CAN_APPLY_UNAPPLY_MULT: There are multiple items that need to be unapplied before this can be applied. Think of switching to a bow but you have a sword & shield - both the sword and shield need to be uneqipped before you can do the bow.
CAN_APPLY_UNAPPLY_CHOICE: There is a choice of items to unapply before this one can be applied. Think of rings - human is wearing two rings and tries to apply one - there are two possible rings he could remove.