/sys$common/syshlp/helplib.hlb FORTRAN, /CHECK, ALIGNMENT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Enables or disables recovery for exceptions caused by access of
  unaligned data by vector instructions.

  If /CHECK=ALIGNMENT is specified, the compiler establishes an
  exception handler for the program; this handler prevents vector
  alignment exceptions from terminating the program and allows
  continued execution at the cost of decreased performance.  At the
  end of program execution, a message is displayed giving the total
  number of vector alignment exceptions handled.