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. 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 granularity below the second. If not, value
    precision is limited to 1 second.