.a:      Archive of the "ar" program (an object library).
.afm:    Adobe Font Manager (?) A Type 1 font in AFM format; ATM-compatible.
.arj:    Unknown type of commpressed archive. There is an "unarj" decompressor.
.bash:   A script in the Born-Again-Shell language.
.bat:    Various kinds of batch command files. (Of M$ heritage.)
.bdf:    A bitmapped font in BDF format.
.bmp:    BMP graphical file. (Of M$Win and OS/2 heritage).
.btm:    Unknown type of executable file.
.c:      C source code.
.cc:     C++ source code.
.cf:     Various kinds of configuration files; usually a text file.
.cfg:    Various kinds of configuration files; usually a text file.          
.cgm:    A non-proprietary vector graphics file format.
.cmd:    Various kinds of command files.
.com:    Various kinds of command files.(Of VAX/VMS and M$ heritage.)
.csh:    A script in the C-Shell language.
.conf:   Various kinds of configuration files; usually a text file.
.cpp:    C++ source code.
.cxx:    C++ source code.
.doc:    Various kinds of documents, usually Unix text files.
.dvi:    TeX output file.
.exe:    Various kinds of executable files; often an M$ OS file.
.h:      C or C++ source code include files.
.g3:     G3 Fax file.
.gif:    GIF graphical file.
.gmo     A GNU-format Machine Object file. See "gettext" info.
.gsf:    Ghostscript Font; Type 1 outline font not for ATM (for Ghostscript 
		only or any PS interpreter)
.gz:     Compressed by the gzip program.
.htm:    Same as .html but usually only as copied from the M$ world.
.html:   Hyper-Text Markup Language file used by WWW browers.
.jpg:    JPEG file.
.ksh:    A script in the Korn-Shell language.
.l:      unknown
.lsm:    An entry of the Linux Software Map.
.lzh:    Commpressed by the lha (LHa/LHarc) program.
.mo      A Machine Object file. See "gettext" info.
.mod:    unknown
.o:      An object (module) file. A compiler output.
.orig:   Usually a backup of the "original" version of a file.
.pdf:    Adobe's Page Description Format file.
.pfa:    Postscript Font A; Type 1 outline font for ATM or any PS interpreter.
.pfb:    Postscript Font B; Type 1 outline font for ATM or any PS interpreter.
.pfm     Postscript Font Manager A Type 1 font in PFM format; ATM-compatible.
.png     Portable Network Graphics (?) (PNG) format file.
.po      A Portable Object file. See "gettext" info.
.pot     Temorary Portable Object file. See "gettext" for info.
.pox     A temporary Portable Object file. See "gettext" for info.
.ps:     Adobe's Postscript language (input) file.
.rar:    unknown; some kind of M$ archive, I suspect.
.rpm:    Archive used with the "rpm" package management program.
.rpmsave:  A backup file created by the "rpm" program.
.sh:     A script in the Bourne shell language.
.sgml:   Structured Generalized Markup Language file.
.so:     Shared Object module (linking) library.
.tar:    An archive of the "tar" program.
.taz:    Unknown type of commpressed file.
.tex:    TeX input file.
.texi:   Input to the texinfo (?) program.
.tgz:    An archive of the "tar" program compressed with the -z option.
.tif:    TIFF
.tiffg3: TIFFG3 Fax file.
.troff:  Input to the troff (text run-off?) program.
.ttf:    TrueType Font.
.txt:    Text file; usually with "^J" (newline) end-of-line markers.
.wav:    Sound data of a certain kind.
.xbm:    XBM graphical file. Monochrome.
.xpm:    XPM graphical file.
.xml:    Extensible Markup Language (?) file.
.zip:    Compressed with one of the "zip" programs.
.Z:      Compressed with the "compress" program.
.z:      Compressed with the "gzip" program, usually.
rc:      Various kinds of configuration files; usually a text file.
.:       tbd