-

If the specified switch name is not defined by the IFDEF control instruction, if the absolute expression of the IF, or ELSEIF control instruction is evaluated as being false (= 0), or if the absolute expression of the IFN, or ELSEIFN control instruction is evaluated as being true ( 0), assembles the arrangement of statements (block) enclosed within this control instruction and the corresponding ENDIF control instruction.

-

With these conditional assembly control instructions, source statements subject to assembly can be changed without major modifications to the source program.

-

If a statement for debugging that becomes necessary only during the program development is described in a source program, whether or not the debugging statement should be assembled (translated into machine language) can be specified by setting switches for conditional assembly.