Question 9818 – GATE 2000

    X: Indirect addressing            1 : Loops
    Y: Immediate addressing           2 : Pointers
    Z: Auto decrement addressing      3: Constants  

Indirect addressing:
Indirect addressing means that the address of the data is held in an intermediate location so that the address is first ‘looked up’ and then used to locate the data itself.
Immediate addressing:
Immediate Addressing. An immediate operand has a constant value or an expression. When an instruction with two operands uses immediate addressing, the first operand may be a register or memory location, and the second operand is an immediate constant.
Auto increment or decrements can be one by using loops.