ARC file header structure

        Byte number      Value(s)        Meaning
        --------------------------------------------------------------
        0                $1A             Header Flag
        1                0-9             Compression method
        2-14             ---             Filename.
        15-18            ---             Compressed file size.
        19-20            bits            Date format
                         15-9            Year
                          8-5            Month
                          4-0            Day
        21-22            bits            Time format
                         15-11           Hours (military)
                         10-5            Minutes
                          4-0            Seconds
        23-24            ---             CRC-16
        25-28            ---             Original file size

        Compression method
        ------------------
        1    unpacked (obsolete)
        2    unpacked
        3    packed
        4    squeezed (after packing)
        5    crunched (obsolete)
        6    crunched (after packing) (obsolete)
        7    crunched (after packing, using faster hash algorithm)
        8    crunched (after packing, using dynamic LZW variations)
        9    Squashed c/o Phil Katz (no packing) (var. on crunching)

        NOTE:    LZW is Lempel-Ziv-Welch compression algorithm