Sometimes you might need to exclude a single file from your project, so that it will be ignored by inspections, code completion, etc. This is done using theaction.
When a file is marked as plain text, IntelliJ IDEA does not use it anymore for code completion and navigation. Such file is shown as plain text in the editor, and is denoted with a special icon in the Project tool window.
This action is not applicable to Java files and binaries.
The reverse action is also available: you can return a file to its original type, using theaction.