Browsers such as Netscape on Unix systems reads, by default, the available mime types and helper applications to use from
(1) system-wide files (typically /usr/local/lib/netscape/mime.types and /usr/local/lib/netscape/mailcap), and
(2) user-specific files (typically .mime.types and .mailcap in the user's home directory).
Recent versions of Netscape, e.g., allow the user to configure the user-specific files from within the browser through the Options menu (usually under General Preferences). However, some earlier versioons (Netscape version 2.0 for instance) does not allow the editing of these files from within the browser itself. In these cases, the user must edit the files manually unless the system-wide files (1) already contain appropriate entries.
To add a mime type maple-v-r4 to be associated with a file name suffix mws, for example, add the following line to your .mime.types file:
application/maple-v-r4 mws
(with a space before mws), and specify the helper application for it by adding the following line to your .mailcap file:
application/maple-v-r4; xmaple %s
(with a space after ; and one before %), assuming that the application xmaple is the executable form of Maple Release 4 and that it is in your path. If it is not in your path, you will have to specify the full path name for it.