Library /sys$common/syshlp/macro$dwci.hlb options, generation, enable, truncation  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Click on the Truncate FP Numbers button to direct the
  assembler to truncate floating-point numbers (if
  truncation is disabled, such numbers are rounded).
  G_floating, D_floating, and H_floating numbers are not
  affected.

  Equivalent qualifier (DCL interface):

     /[NO]ENABLE=TRUNCATION
     /[NO]DISABLE=TRUNCATION