The seven vowel orders of the fidel have names, and the names are Ge'ez ordinals: the first is ge'ez, the second ka'eb, the third salis, the fourth rabi', the fifth hamis, the sixth sadis and the seventh sabi'. Rabi', the fourth, begins with this letter.
Those names are a small piece of evidence about how the system was understood by the people who used it. They are not descriptions of vowels. Nobody named an order after the sound it carries. They are positions in a row, counted, which means the row itself is the unit being taught. A letter is a row of seven, recited across, and a vowel is identified by where it falls in the recitation rather than by any name of its own. A speaker asked which order a sign belongs to answers with an ordinal, not with a vowel.
The first order name is the same word as the name of the language, ge'ez, which in this use carries the sense of the plain or unmodified form. A child reciting the grid begins each row in the ge'ez order and works across it. The atlas holds the twenty-six rows as its letters and treats the orders as a property of the script rather than as separate entries, which follows the way the fidel is actually taught and chanted rather than the way a character table lists it.