Note that no logographic script is composed solely of logograms. It also contained syllabic signs and logograms. Some Sumerian logograms were written with multiple cuneiform signs. In the 1930s some individual logograms and syllabic signs were correctly identified. He first experimented with logograms, before developing his system into a syllabary. In Old Coptic, there were a large number of Demotic Egyptian characters, including some logograms. However, the latest cuneiform texts are almost entirely written in Sumerian logograms. The use of pictograms and logograms in texts are present in every language. Finally, cuneiform writing became a general purpose writing system for logograms, syllables, and numbers. The Chinese logograms for "peng" and "kun" exemplify common radical-phonetic characters. In Maya writing, logograms and syllable signs are combined. The glyphs themselves are highly detailed, and particularly the logograms are deceivingly realistic. As Njoya revised the script, he introduced logograms (word symbols). Chinese characters are basically logograms constructed with strokes. The usage of logograms is not obligatory.