## Chapter 10. Mode Definition Syntax

Edit modes are defined using XML, the extensible markup language; mode files have the extension `.xml`. XML is a very simple language, and as a result edit modes are easy to create and modify. This section will start with a short XML primer, followed by detailed information about each supported tag and highlighting rule.

Editing a mode or a mode catalog file within jEdit will cause the changes to take effect immediately. If you edit modes using another application, the changes will take effect after the Utilities>Reload Edit Modes command is invoked.