From the NannyMUD documentation

LAST CHANGE

2001-08-12

FUNCTION

NAME
        _acl_str2num - Convert a given ACL string to the corresponding number.


SYNTAX
        int _acl_str2num(string str)

DESCRIPTION
        Given a string, return the ACL number 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. PX means 129 and 
        PDALURWX gives 255.