This Annex describes features for writing mixed-language programs. General interface support is presented first; then specific support for C, COBOL, and Fortran is defined, in terms of language interface packages for each of these languages. 

Support for interfacing to any foreign language is optional. However, an implementation shall not provide any optional aspect, attribute, library unit, or pragma having the same name as an aspect, attribute, library unit, or pragma (respectively) specified in the subclauses of this Annex unless the provided construct is either as specified in those subclauses or is more limited in capability than that required by those subclauses. A program that attempts to use an unsupported capability of this Annex shall either be identified by the implementation before run time or shall raise an exception at run time.