Derivations from Two-Level Grammars have been defined only in terms of the infinite context-free grammars that can be generated from them. This fact has proven a severe theoretical obstacle to solving the parsing problem for two-level grammars. So far, partial solutions exist for Van Wijngaarden Grammars, Extended Affix Grammars, and Affix Grammars which allow parsing in a single pass from left to right, because these special cases could be handled without developing a full theory of parsing for two-level grammars.