it was call "bit flags". can store mutiple value at once.
example:
A = 0x1
B = 0x2
C = 0x4
D = 0x8
you need to store ABC on variable ItemAttr.
ItemAttr = 1+2+4 (so it was 7)
when you need to try compare value with c++.
you can use & for check bit flags, also use | for set mutiple flags
if(ItemAttr & A)
ItemAttr = A | B | C