27.2.2.1 Customization Groups

For customization purposes, user options are organized into groups to help you find them. Groups are collected into bigger groups, all the way up to a master group called Emacs.

M-x customize (or C-h C) creates a customization buffer that shows the top-level Emacs group and the second-level groups immediately under it. It looks like this, in part:

/- Emacs group: ---------------------------------------------------\
      [State]: visible group members are all at standard settings.
   Customization of the One True Editor.
   See also [Manual].

 [Open] Editing group
Basic text editing facilities.

 [Open] External group
Interfacing to external utilities.

more second-level groups

\- Emacs group end ------------------------------------------------/

This says that the buffer displays the contents of the Emacs group. The other groups are listed because they are its contents. But they are listed differently, without indentation and dashes, because their contents are not included. Each group has a single-line documentation string; the Emacs group also has a ‘[State]’ line.

Most of the text in the customization buffer is read-only, but it typically includes some editable fields that you can edit. There are also active fields; this means a field that does something when you invoke it. To invoke an active field, either click on it with Mouse-1, or move point to it and type RET.

For example, the phrase ‘[Open]’ that appears in a second-level group is an active field. Invoking the ‘[Open]’ field for a group opens up a new customization buffer, which shows that group and its contents. This field is a kind of hypertext link to another group.

The Emacs group does not include any user options itself, but other groups do. By examining various groups, you will eventually find the options and faces that belong to the feature you are interested in customizing. Then you can use the customization buffer to set them.

You can view the structure of customization groups on a larger scale with M-x customize-browse. This command creates a special kind of customization buffer which shows only the names of the groups (and options and faces), and their structure.

In this buffer, you can show the contents of a group by invoking ‘[+]’. When the group contents are visible, this button changes to ‘[-]’; invoking that hides the group contents.

Each group, option or face name in this buffer has an active field which says ‘[Group]’, ‘[Option]’ or ‘[Face]’. Invoking that active field creates an ordinary customization buffer showing just that group and its contents, just that option, or just that face. This is the way to set values in it.