1. A computer-implemented method comprising: obtaining a regular language for XML next generation (RNG) file referencing an RNG schema file; storing the referenced RNG schema file in a file directory structure matching a reference definition of the schema in the RNG file; and generating, based on the RNG file, a first nonextensible schema and a first extensible schema each corresponding to the referenced RNG schema file, wherein obtaining the RNG file comprises: obtaining a second nonextensible schema including a first content model of ANY; generating, based on the second nonextensible schema, a compact syntax regular language for XML next generation (RNC) file including a second content model of ANY, the second content model of ANY corresponding to the first content model of ANY; modifying, based upon the RNC file including the second content model of ANY, the RNC file so as to explicitly enumerate all semantics of the second content model of ANY as elements in the RNC file; and generating, based on the modified RNC file, the RNG file.