The royal cubit was considered sacred and used to determine the dimensions of temples. I found the hieroglyphics for a tcheser length in Wallis Budge's Egyptian Hieroglyphic Dictionary which confirms its special status. The name also suggests a connection with the Eye of Horus fractions mentioned earlier. It could be that tcheser conveys the meanings hallowed, exalted and royal. There is a sense of truth and justice associated with it also. Copies were made of the royal cubit for the use of workers and compared with the original monthly. The penalty for tampering with the royal cubit was death. For more information see Thoth: Architect of the Universe by Ralph Ellis.