Xor

Takes the two top values on the conditions stack and xor's them together. If one of them is true and one is false it puts true on the stack. If both are true, or if both are false, it puts false on the stack.

0 0 and puts 0 on the stack
1 0 and puts 1 on the stack
0 1 and puts 1 on the stack
1 1 and puts 0 on the stack

Logic: true false and or not xor