From the NannyMUD documentation

LAST CHANGE

2001-08-12

FUNCTION

NAME
        _acl_num2str - Convert a given ACL number to the corresponding string.


SYNTAX
        string _acl_num2str(int num)

DESCRIPTION
        Given a number, return the ACL string it corresponds to. The
	values and strings are as follows:

	    0      NONE
	    1      P
	    2      D
	    4      A
	    8      L
	   16      U
	   32      R
	   64      W
	  128      X
	  256      T
        65535      ALL

	The values are logically "or"-ed together, i.e. 129 gives PX
	and 255 gives PDALURWX.