Memory space attributes become important when an expression is used as an address. Errors occur when the memory space attribute of the expression result does not match the explicit or implicit memory space specified in the source code. Memory spaces are explicit when the address has any of the following forms:
X: address expression
P: address expression
The memory space is implic itly P when an address is used as the operand of a DO, branch, or jump-type instruction.
Expressions used for immediate addressing can have any memory space attribute.