The result of over twenty years of research, the Common European Framework of Reference for Languages: Learning, teaching, assessment (CEFR) is exactly what its title says it is: a framework of reference. It was designed to provide a transparent, coherent and comprehensive basis for the elaboration of language syllabuses and curriculum guidelines, the design of teaching and learning materials, and the assessment of foreign language proficiency.
R. Schank, and R. Abelson. Thinking: Readings in Cognitive Science, Proceedings of the Fourth International Joint Conference on Artificial Intelligence, page 151-157. Tbilisi, USSR, (1975)