COMPUTE DATE

        [SIC\]COMPUTE Modification_Date DATE Filename

    Return  the last modification date of the file Filename into the integer
    variable Modification_Date. Used in procedures to check  when  file  has
    last been changed.

    If the output variable is a 4-bytes integer (Fortran I*4), returned val-
    ue is in seconds since 01-jan-1970. As the  value  will  overflow  after
    19-JAN-2038,  this  syntax  is  obsolescent  and will be removed at some
    point. Consider using I*8 output variable (in nanoseconds)  or  the  SIC
    MODIFIED command.

    If the variable is a 8-bytes integer (Fortran I*8), returned value is in
    nanoseconds since 01-jan-1970. In the latter  case,  your  system  (e.g.
    Linux >= 2.5.48) AND filesystem (e.g. ext4) must support timestamp gran-
    ularity below the second. If not, value precision is limited to  1  sec-
    ond.