The move to MCSG is motivated by our desire to more perspicuously account for certain syntactic phenomena that cannot be easily captured by context-free grammars, such as clitic climbing, extraposition, and other types of longdistance movement (Becker et al., 1991).
mCSG still observes some restrictions that make the set of languages it generates less ex-pensive to analyze than the languages generated by (properly) context-sensitive formalisms.