File created by BlueJ, a Java language development environment; automatically generated by BlueJ during compilation; contains extra information for a class such as the comments structure and documentation for methods in the code; only one CTXT file can accompany each class.

Once you compile your specific class, the CTXT file will be created and appear in the same location as your .CLASS file. NOTE: Whenever changes are made to the source file, they will be reflected in the CTXT files after the next compile.