The .Xdefaults-hostname file, located in $HOME, defines resource specifications for clients invoked by an individual user. hostname refers to the name of the machine on which the clients are running.
If you run clients on multiple hosts, you need to create an .Xdefaults-hostname file on each host.
The $HOME/.Xdefaults-hostname file is not created by default. If you want to specify your own individual resources, you must first create this file.
The .Xdefaults-hostname file overrides
default resource specifications that are defined in
client-specific resource files, located in
/usr/lib/X11/app-defaults. These files take
the name client, where the client's class
name is used.
For example, the ScoHelp file contains resource
specifications for the DocView help system, and the
ScoTerm file contains resource specifications
for the scoterm client.
Finally, individual users can create client-specific resource files that only control the clients they run without affecting other users on the system. As in the /usr/lib/X11/app-defaults directory, these files use a client's class name as their filename; however, they are located in the user's home directory.
For example, if you want to define several unique Desktop resources and store them in your own personal client-specific resource file, you would name the file $HOME/XDesktop3.