For modification types R, RI, and IR the tag designator contains a register to be used for indexing (X0-X7,AU,AL,QU,QL,IC). Other TD values indicate that Y should be used as an immediate operand. Direct addressing is a special case where Y is used as the operand address with no modification.
for modification types r ri and ir the tag designator contains a register to be used for indexing (x0-x7aualquqlic) other td values indicate that y should be used as an immediate operand direct addressing is a special case where y is used as the operand address with no modification