libIDL is a library licensed under the GNU LGPL for creating trees of CORBA Interface Definition Language (IDL) files, which is a specification for defining portable interfaces. libIDL was initially written for ORBit (the ORB from the GNOME project, and the primary means of libIDL distribution). However, the functionality was designed to be as reusable and portable as possible. It is written in C, and the aim is to retain the ability to compile it on a system with a standard C compiler. Preprocessed parser files are included so you are not forced to rebuild the parser, however an effort is made to keep the parser and lexer compatible with standard Unix yacc. Currently, flex is required to generate the lexical scanner. With libIDL, you can parse an IDL file which will be automatically run through the C preprocessor (on systems with one available), and have detailed error and warning messages displayed. On a compilation without errors, the tree is returned to the custom application. libIDL performs compilation phases from lexical analysis to nearly full semantic analysis with some optimizations, and will attempt to generate meaningful errors and warnings for invalid or deprecated IDL.