1 * .lzh -- Old MS-DOS or FidoNET user, should probably stop playing with computers
3 * .lha -- Conservative Amiga user
4 * .lzx -- Progressive Amiga user
5 * .xpk -- Advanced Amiga user
7 * .tar.gz -- Average UNIX user
8 * .tar.bz2 -- Modern UNIX user, usually GNU/Linux
9 * .tar.Z -- Old fashioned UNIX die-hard.
10 * .cpio -- Solaris or someone stuck with an old SVR4 UNIX
11 * .tar -- Lazy people who would waste bits disrespectfully