Undefine register symbol directive

    Format

      .UNDEFINE_REG  regsym

1  –  Parameter

 regsym

    A currently defined floating-point or integer register symbol.

2  –  Description

    The register symbol that you specify as the argument to the
    .UNDEFINED_REG directive is no longer a register symbol. Starting
    with the statement that follows the .UNDEFINE_REG directive, you
    can use the symbol as a MACRO-64 identifier.

3  –  Notes

    o  If you specify a MACRO-64 identifier that is not currently
       defined as a register symbol, the .UNDEFINE_REG directive has
       no effect.

4  –  Example

           .DEFINE_IREG  X1    R5      ; X1 is integer register 5
           .UNDEFINE_REG X1            ; X1 is an identifier again
           .DEFINE_IREG  X1    7       ; X1 is integer register 7 -
 no
                                        ;  redefinition and no warning

            $ROUTINE F0                 ; Error: F0 is a register and
                                        ;  cannot be used as an
                                        ;  identifier
            .UNDEFINE_REG F0            ; F0 is no longer a register
            $ROUTINE F0                 ; Ok now