Syntactic elements or the nonterminal elements for human promoter region.

G→ Gap i.e., parts of DNA sequences that are not of our interest or their significance is still not known. Here a gap in the grammar rule defines some length of bases flanked by two subsequence of interest. In the grammar rules, the symbol G (any) is used to specify a gap of indefinite length whereas when gap length is known to be within a range, gap (#Lower Limit, Upper Limit#) is preferred.