Basically, a extension map is a configuration file that maps file
extensions to MIME types. An example would
be mapping file extension ".gif" to MIME type image/gif.
Here is an example extension map file:
application/postscript ai eps ps application/rtf rtf application/slate application/x-tex tex application/x-texinfo texinfo texi application/x-troff t tr roff audio/basic au snd audio/x-aiff aif aiff aifc audio/x-wav wav image/gif gif image/ief ief image/jpeg jpeg jpg jpe image/tiff tiff tif image/x-xwindowdump xwd text/html html text/plain txt video/mpeg mpeg mpg mpe video/quicktime qt mov video/x-msvideo avi video/x-sgi-movie movie
Note that each MIME type can be mapped to zero or more file extensions.
Note also that extension mapping is case insensitive.
Note finally that comments (lines starting with "#") are not supported until 2.0 prerelease 6, and that leading whitespace is not allowed -- the first character of the content-type should be the first character on a line.
globalExtensionMap gives the filename. The default is
"/usr/local/lib/mosaic/mime.types". This is generally the location
for system- or site-wide viewer configuration.
There can also be a personal extension map; the X resource
personalExtensionMap gives the filename (the value of the
environment variable HOME is prepended to this). The
default is ".mime.types". This is generally the location for per-user
configuration.
Note that Mosaic is configured to map some extensions to MIME types by
default. To turn off these defaults, set the
X resource useDefaultExtensionMap to false. We
strongly recommend that this resource be left true; simply
override as necessary.
Entries in the personal extension map take precedence over entries in the global extension map, which in turn take precedence over the built-in defaults.
For information on file extensions mapped to MIME types by default in Mosaic 2.0pre4, see here.
For the list of MIME types recognized by default by Mosaic 2.0pre4, see here.