Complex sentence: A graphical language which is devised as a counterpart to a spoken or written language is not constrained by some of the limitations of spoken languages and can extend the usefulness of the spoken language as the written extension of the spoken language is.
Split into simpler sentences: A graphical language which is devised as a counterpart to a spoken or written language is not constrained by the limitations of spoken languages. It extends the usefulness of the spoken language as the written extension of the spoken language is.