19.1 Common Keywords for All Kinds of Items

All kinds of customization declarations (for variables and groups, and for faces) accept keyword arguments for specifying various information. This section describes some keywords that apply to all kinds.

All of these keywords, except :tag, can be used more than once in a given item. Each use of the keyword has an independent effect. The keyword :tag is an exception because any given item can only display one name.

:tag name

Use name, a string, instead of the item’s name, to label the item in customization menus and buffers.

:group group

Put this customization item in group group. When you use :group in a defgroup, it makes the new group a subgroup of group.

If you use this keyword more than once, you can put a single item into more than one group. Displaying any of those groups will show this item. Be careful not to overdo this!

:link link-data

Include an external link after the documentation string for this item. This is a sentence containing an active field which references some other documentation.

There are three alternatives you can use for link-data:

(custom-manual info-node)

Link to an Info node; info-node is a string which specifies the node name, as in "(emacs)Top". The link appears as ‘[manual]’ in the customization buffer.

(info-link info-node)

Like custom-manual except that the link appears in the customization buffer with the Info node name.

(url-link url)

Link to a web page; url is a string which specifies the URL. The link appears in the customization buffer as url.

You can specify the text to use in the customization buffer by adding :tag name after the first element of the link-data; for example, (info-link :tag "foo" "(emacs)Top") makes a link to the Emacs manual which appears in the buffer as ‘foo’.

An item can have more than one external link; however, most items have none at all.

:load file

Load file file (a string) before displaying this customization item. Loading is done with load-library, and only if the file is not already loaded.

:require feature

Require feature feature (a symbol) when installing a value for this item (an option or a face) that was saved using the customization feature. This is done by calling require.

The most common reason to use :require is when a variable enables a feature such as a minor mode, and just setting the variable won’t have any effect unless the code which implements the mode is loaded.