Programs running under the X Window System organize their user options under a hierarchy of classes and resources. You can specify default values for these options in your X resources file, usually named `~/.Xdefaults'.
Each line in the file specifies a value for one option or for a collection of related options, for one program or for several programs (optionally even for all programs).
Programs define named resources with particular meanings. They also define how to group resources into named classes. For instance, in Emacs, the `internalBorder' resource controls the width of the internal border, and the `borderWidth' resource controls the width of the external border. Both of these resources are part of the `BorderWidth' class. Case distinctions are significant in these names.
In `~/.Xdefaults', you can specify a value for a single resource on one line, like this:
Or you can use a class name to specify the same value for all resources in that class. Here's an example:
If you specify a value for a class, it becomes the default for all resources in that class. You can specify values for individual resources as well; these override the class value, for those particular resources. Thus, this example specifies 2 as the default width for all borders, but overrides this value with 4 for the external border:
emacs.Borderwidth: 2 emacs.borderwidth: 4
The order in which the lines appear in the file does not matter. Also, command-line options always override the X resources file.
The string `emacs' in the examples above is also a resource name. It actually represents the name of the executable file that you invoke to run Emacs. If Emacs is installed under a different name, it looks for resources under that name instead of `emacs'.
When Emacs creates a new frame, it may or may not have a specified title. The frame title, if specified, appears in window decorations and icons as the name of the frame. It is also used (instead of the Emacs executable's name) to look up all the resources for that frame. The option `-name' specifies a frame title for the initial frame. Subsequent frames normally have no specified frame title, but Lisp programs can specify a title when they create frames.
For consistency, `-name' also specifies the name to use for other resource values that do not belong to any particular frame.
The resources that name Emacs invocations also belong to a class; its name is `Emacs'. If you write `Emacs' instead of `emacs', the resource applies to all frames in all Emacs jobs, regardless of frame titles and regardless of the name of the executable file. Here is an example:
Emacs.BorderWidth: 2 Emacs.borderWidth: 4
You can specify a string of additional resource values for Emacs to use with the command line option `-xrm resources'. The text resources should have the same format that you would use inside a file of X resources. To include multiple resource specifications in data, put a newline between them, just as you would in a file. You can also use `#include "filename"' to include a file full of resource specifications. Resource values specified with `-xrm' take precedence over all other resource specifications.
The following table lists the resource names that designate options for Emacs, each with the class that it belongs to:
Here are resources for controlling the appearance of particular faces (see section Using Multiple Typefaces):