The Algol 68 syntax is defined with the two-level grammars of A. van Wijngaarden which generate recursively enumerable sets, their recognition problem being generally algorithmically insolvable. The original grammar of Algol 68 could be considered only as a document. An effective method for the analysis of Algol 68 had to be found on the basis of others more simple classes of grammars, and an adequate tool for its implementing had to be built. Later the tool was implemented in the technological complex SYNTAX.