VMS Help FORTRAN, Data, Constants, REAL_16  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  A REAL*16 constant can be a basic real constant or an integer
  constant followed by a decimal exponent.  A decimal exponent has
  the form:

     Qsnn              s is an optional sign
                       nn is a string of decimal digits