Appendix A. Working with Syntax Highlighting

Table of Contents

The Kate Syntax Highlight System
How it Works
Context Styles and Keywords
Default Styles
The Highlight Definition XML Format
The Sections in Detail
Available Default Styles
Highlight Detection Rules
The Rules in Detail
Tips & Tricks


Syntax Highlighting is what makes the editor automatically display text in different styles/colors, depending on the function of the string in relation to the purpose of the file. In program source code for example, control statements may be rendered bold, while data types and comments get different colors from the rest of the text. This greatly enhances the readability of the text, and thus helps the author to be more efficient and productive.

A Perl function, rendered with syntax highlighting.

A Perl function, rendered with syntax highlighting.

The same Perl function, without highlighting.

The same Perl function, without highlighting.

Of the two examples, which is easiest to read?

Kate comes with a flexible, configurable and capable system for doing syntax highlighting, and the standard distribution provides definitions for a wide range of programming, scripting and markup languages and other text file formats. In addition you can provide your own definitions in simple XML files.

Kate will automatically detect the right syntax rules when you open a file, based on the MIME Type of the file, determined by its extension, or, if it has none, the contents. Should you experience a bad choice, you can manually set the syntax to use from the ToolsHighlighting menu.

The styles and colors used by each syntax highlight definition can be configured using the Highlighting Text Styles tab of the Config Dialog, while the MIME Types and file extensions it should be used for are handled by the Modes & Filetypes tab.


Syntax highlighting is there to enhance the readability of correct text, but you cannot trust it to validate your text. Marking text for syntax is difficult depending on the format you are using, and in some cases the authors of the syntax rules will be proud if 98% of text gets correctly rendered, though most often you need a rare style to see the incorrect 2%.


You can download updated or additional syntax highlight definitions from the Kate website by clicking the Download Highlighting Files... button in the Modes & Filetypes tab of the Config Dialog.