VMS Help MACRO, VAX MACRO Assembler, Directives, .IF TRUE (.IFT)  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Starts a  subconditional  assembly  block  to  be  assembled  if
    the condition  test  specified  when  the  conditional assembly
    block was entered was true.  The subconditional assembly block that
    starts with .IF_TRUE  continues  up to the next subconditional
    assembly directive or to the end of the conditional assembly block.

      .IF_TRUE

    The alternate form of .IF_TRUE is .IFT.