User Defined Languages

What are User Defined Languages

Notepad++ comes prepackaged with many Language lexers, which apply syntax highlighting to source code or textual data. However, not every possible language or formatting style is available. Enter the User Defined Languages (or “UDL” for short): the UDL interface allows the user to define rules for formatting normal text, keywords, comments, numbers; to define delimiters (like quotes around strings or parentheses around lists) which will cause text between those delimiters to be formatted; and to define symbols or keywords that can be used to allow folding (on-demand hiding and unhiding of blocks of code or text).

UDL Dialog Box or Window

The Languages menu on the menu-bar includes the list of builtin languages, and below those are a separator followed by Define Your Language… and a list of any UDL that have been already defined.

Using Languages > Define Your Language… will bring up a dialog box (which can be docked as a pane in the Notepad++ Window, or can be a floating dialog box).

The main pulldowns and buttons are available, whichever configuration tab is active: * User Language pulldown lists all the existing UDL will allow you to select the UDL you would like to edit or examine. There is a special entry for the default UDL, called User Defined Language here (though it shows up in the Notepad++ Languages menu as User-Defined), which can be used as a template for other UDL. * Create New will copy the default User Defined Language stylings and rules to a new name. * Save As will copy the currently-selected UDL, with all its stylings and rules, to a new name. * Import… will import a UDL XML file into your current instance (see below). * Export… will save a UDL XML file to a location of your choosing; you can then share this with others, so that they can import your UDL for their own use. * Dock or Undock will toggle whether the UDL dialog is a standalone dialog, or docked in the Notepad++ window. * ☐ Ignore Case will make the various keywords ignore case while matching. * ☐ Transparency (when not docked) will make the dialog box semi-transparent; the slider bar changes from virtually invisible (all the way to the left) to mostly opaque (all the way to the right); if you want it completely opaque (no transparency), uncheck the box.

When a UDL other than the default User Defined Language is seelcted in the pulldown, the following will also be available: * Rename will rename the currently-selected UDL. * Remove will delete the currently-selected UDL. * Ext.: ____ will accept a list of zero or more extensions (without the period). Files that match these extensions will be interpreted as belonging to the currently-selected UDL, and will be styled appropriately. These extensions override the default extensions for pre-defined Languages, so if your UDL’s extension conflicts with another language’s extension, the UDL will take priority. For example Ext.: md mkdn will associate file.mkdn or with your selected UDL.

UDL Configuration Tabs

Ivan Radić has created the definitive guide to the nuts and bolts of UDL version 2.1, which is available at He explains the details of what each of the tabs in the User Defined Language dialog box will do, and how to use them to style your various keywords. However, these descriptions will give you an overview of what each tab is for.

  • The Folder & Default tab allows setting the default style, setting up keywords (or characters) that will allow code folding, and setting up styles for those keywords. The Open, Middle, and Close boxes under each folding-type define the triggers for the start, middle, and end of folding. For example, with if, else, and endif, it will define fold regions so that you can fold from if to else, from else to endif, and (assuming there is no else clause) from if to endif. Folding in comment allows comments to include folding; Folding in code 1 style allows the triggers to be touching something else (so with a trigger of {, it will match if{ or if {), whereas Folding in code 2 style requires there be whitespace around the trigger (so if{ would not match an Open-trigger of {).

  • The Keywords List tab allows defining eight (8) different groups of keywords, so you can style different groups of words differently (like builtin functions vs. flow control keywords). Separate each keyword by a space (and that means that spaces are not allowed in keywords unless you put quotes around the phrase). If ☐ Prefix Mode is enabled for a given group, that means that it will match anything that starts with your string (so a keyword of for would match for, forth, and format if that option is enabled).

    As a point of interest, you shouldn’t have a given keyword in more than one keyword-group or folder-group. If you want if/else/endif to cause block-folding, do not also put them in one of your keyword-groups.

  • The Comment & Number tab allows setting styles for comments and for numbers.

    • Line Comment Position allows you to decide whether “line comments” can start anywhere on the line, must start at the beginning, or can start anywhere on the line as long as it’s only whitespace before the comment.
    • ☐ Allow folding of comments will enable comments to be foldable.
    • Comment line style defines the style for “line comments” – comments that proceed from the opening-trigger to the end of the line.
    • Comment style defines the style for multiline-comments.
    • Number style defines the style for numbers. The various Prefixes, Suffixes, and Extras allow you to define extra numeric representations (useful for hexadecimal, binary, octal and similar representations, as well as for defining currency as a number). The Range allows you to define a syntax for ranges, so that two numbers with a listed token in between will still be treated as a number. (However, there may be conflicts if the Range setting matches one from Operators & Delimiters
  • The Operators & Delimiters tab allows setting styles for operators and for delimiter pairs

    • Operators 1 and Operators 2 define two groups of operators (usually math and math-like operators). The first defines operators that will be matched even if they are touching other characters (allowing 1+2), whereas the second defines operators that must contain spaces to be recognized (like 1 + 2).
    • The various Delimiter styles are pairs of Open and Close characters, where those characters and whatever comes between them will be styled per the rules defined for that entry. This is useful for styling strings, parenthesized parameter lists, bracketed expressions, and anything else where it can have a . The Escape entry allows defining a way of “escaping” the character so that the delimiter pair is not prematurely closed (such as " / \ / " allowing "this \" is an embedded quote character inside a string, escaped by the backslash").

Import a UDL

The internet has plenty of Notepad++ UDL xml files. Once you have the XML, you can then import it into your Notepad++, so that you can use that UDL yourself. There are two main ways to do this:

  1. Copy the XML into the appropriate userDefineLangs subfolder. Exit all instances of Notepad++ and reload, then the new UDL will be available.

  2. Use the Import… button, navigate to the source XML, and the UDL will be immediately available.

The differences between those two methods are when the UDL will be available to Notepad++, and which config file will hold that UDL, per UDL File Locations.

UDL File Locations

Individual UDL files are stored in one of two userDefineLangs subfolders. Each XML file in that folder is used to define one or more UDL.

  1. %AppData%\Notepad++\userDefineLangs: this is the default location for most Notepad++ installations
  2. <notepad++_directory>\userDefineLangs: this is the location for portable versions, or if you turned on “local configuration mode” (or disabled %AppData%) during the installation. <notepad++_directory> refers to whatever folder the notepad++.exe application executable is located.

If you created or imported a UDL using the User Defined Languages dialog inside Notepad++, they will be in the userDefineLang.xml file. This single file often holds multiple UDL definitions.

  1. %AppData%\Notepad++\userDefineLang.xml: this is the default location for most Notepad++ installations
  2. <notepad++_directory>\userDefineLang.xml: this is the location for portable or “local configuration mode” versions, as described above

UDL and Themes

The User Defined Languages are not affected by your active theme.

However, since you can set the colors of a UDL to whatever you want, you can manually make it match your theme. If you want to define multiple UDL using the same basic color scheme, you can start by setting the colors of the default User Defined Language, then Create New for each UDL that you want to match that scheme, customizing the rules for each new UDL.

User Defined Languages Collection

Throughout the history of Notepad++, many UDL files have been created by Notepad++ users and made publically available. There is once again a centralized User Defined Languages Collection.

This central Collection is a convenient location for UDL-users to find new UDL files, and for UDL-authors to share their UDL files with the whole Notepad++ community. The Collection includes instructions for how to use the files, as well as how to submit new UDL to the Collection.

UDL Configuration File Contents

It is intended that UDL are edited using the GUI dialog boxes. However, if you are the type of user who likes to configure Notepad++ through the configuration files, it is possible. Please see the Configuration Files Details for a description of the sequence for properly editing any of the config files, including the UDL definition files.

Most of the settings in the UDL definition files correspond directly to the names seen in the User Defined Languages dialog box, or the Styler sub-dialog. The <KeywordLists> section defines the keywords or symbols for each highlighting category. The <Styles> section defines the text styling (color, font, weight, and decoration) for each highlighting category. The <WordsStyle> fontStyle attribute encodes the setting of the Bold, Italic, and Underline checkboxes from the Styler dialog, using the sum of Italic=1, Bold=2, and Underline=4 (so something with all three checkboxes set would have fontStyle="7"). The nesting attribute similarly encodes the various nesting checkboxes from the Styler dialog with a sum of the values below, and indicate which styles will nest properly inside the active style:

Checkbox Value Checkbox Value Checkbox Value
Delimiter 1 1 Keyword 1 1024 Comment 256
Delimiter 2 2 Keyword 2 2048 Comment Line 512
Delimiter 3 4 Keyword 3 4096 Operators 1 16777216
Delimiter 4 8 Keyword 4 8192 Operators 2 33554432
Delimiter 5 16 Keyword 5 16384 Numbers 67108864
Delimiter 6 32 Keyword 6 32768
Delimiter 7 64 Keyword 7 65536
Delimiter 8 128 Keyword 8 131072