Extended LL(k) grammars and parsers

A class of context-free grammars, called "Extended LL(k)" or ELL(k), is defined. This class has been shown to include LL(k) grammars as proper subset, and there are some grammars which are ELL(k) grammars but not LALR(k) grammars.An algorithm to construct persers for ELL(k) grammars is proposed in this paper.Before this paper had been completed, PL/O language was taken as a sample. A parser was constructed for it by ELL(k) technique.