Used by the routine at 7C02. Bit set=got, bit reset=haven't.

Bit	Item	Set	Reset	Checked
0	Safe key	7854		5D63, 7854
1	Science Lab storeroom key	5DDC		5DDC, 73F1, 7615, 7A16
2	Frog	7BF5	7316	7316
3	Water pistol (with water if bit 4 reset)	F2E2	5D37	5D37, 5D63, F99A
4	Water pistol with sherry	5D63	5D37	5D37, 5D63, F99A, FA4D
5	3 stinkbombs	F2E2	F862
6	2 stinkbombs	F2E2	F862
7	1 stinkbomb	F2E2	F862	7140