#### 16.6.4 Executing external tools

The user has now specified the default switches he wants to use for the external tool. Spawning the external tool can be done either from a menu item, or as a result of a key press.

Both cases are described in an XML customization file, as described previously, and both are setup to execute what GPS calls an action, i.e. a set of commands defined by the `<action>` tag.