Akkadian language
The cuneiform sign for the syllable ab also represents that for ap, or the vowel and consonant usages of a, b, or p: in the Akkadian language "b" is unaspirated, formed with the lips, and "p" is aspirated, with the breath). In the Akkadian language "b" and "p" are interchangeable; also, in cuneiform texts, any vowel (a, e, i or u: there is no "o" in Akkadian) can be interchanged with any other. The ab/ap sign also has a corresponding capital letter (majuscule) usage as a sumerogram, as found in the "Epic of Gilgamesh" for AB, the Akkadian language for "šību", meaning "elder".