LJ::get_cap — Given a user object, capability class key or capability class bit mask and a capability/limit name, returns the maximum value allowed for given user or class, considering all the limits in each class the user is a part of.
u_cap. 16 bit capability bitmask or a user object from which the bitmask could be obtained
capname. the name of a limit, defined in Section 4, “Setting Capabilities”.