Some new features of C++ not only introduce incompatibilities with previous versions of C++ but also with C; however, the organization of Annex Clause Annex C [diff] makes it difficult to specify that a given feature is incompatible with both languages, and the practice has been only to document the C++ incompatibilities. Some means of specifying both sets of incompatibilities should be found, hopefully without excessive duplication between the C and C++ sections.