Before you decide to hack the syntax file, or create additions in your after/syntax directory, be sure to check to make sure your desired behavior doesn't already exist as a configurable option in the default syntax file. A good starting point would be to look up the help page on the syntax file. For our example, use [Regardless of how you find them, you can set values for these custom options in your vimrc, or in your own ftplugin directory, to run before the normal ftplugin for the filetype. See [help ftplugin].