The cuneiformšu sign is a common, multi-use syllabic and alphabetic sign for šu, š, and u; it has a subsidiary usage for syllabic qat; it also has a majuscule-(capital letter) Sumerogram usage for ŠU, for Akkadian language "qātu", the word for "hand".[2] The cuneiform character šu is shaped like a human hand and was created late 4th millennium BC or early 3rd millennium BC.
The scribal usage of a sign allows for any of the 4 vowels (there is no vowel 'o' in Akkadian), a, e, i, u to be interchangeable; thus a usage for syllabic qat could conceivably be used for the following (k can replace 'q', and d can replace 't'): q, a, or t; also ka, qa, ad, at. (The "š" (shibilant s) is also interchangeable with the other two esses, "s", and "ṣ", for "šu"!)