From the NannyMUD documentation

LAST CHANGE

2000-12-14

FUNCTION

NAME
        test_bit - Test a given bit in a bitfield.


SYNTAX
	int test_bit(string bitfield, int bitnum)

DESCRIPTION
	Tests a bit with the number 'bitnum' in a specifically coded string
	'bitfield'. The bitfield string is a string consisting of writable
	characters. Each character represents six bits.

	test_bit returns 1 if the bit is set, otherwise 0.


NOTE
	There is a maximum bitindex number which can be changed in config.h
	in the gamedriver source. This constant is normally 1200.