Library /sys$common/syshlp/basichelp.hlb UNLESS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  UNLESS modifies a statement so that the statement is executed only if  a
  conditional expression is false.

  Example

  PRINT "A% does not equal 3" UNLESS A% = 3%

  Additional Information (explode) :

• Syntax