1.1. The Alphabet
The script used in the inscriptions consists of runelike characters mostly formed with vertical and oblique lines. There are also curved lines in some characters, but horizontal lines are very few.
1.11. The Characters
The old Turkic script used in the Orkhon inscriptions consists of 38 characters; combined with two syllabic characters, each of which has been used only once in the inscription of Tonyukuk, the total becomes 40.
Of the 38 characters generally used, 4 are vowel signs. Each vowel sign expresses two different vowels; more precisely, there is only one letter for the vowels a and a, one for i and i, one for and u, and finally one for o and u. The double consonant-characters system of the alphabet and the vocalic harmony prevent possible mistakes in reading the vowels a, a and i, i; but there is no criterion by which one could distinguish between the vowels o and u, and o and ü.
Of the remaining characters, 20 are double ‘conson-ant-characters1 (syllabic characters) which designate syllables beginning with a or a and ending in the characteristic consonant. They can also represent the consonants alone. These characters are: ab, ab; ad, ad; ay, ag; aq, ak; al, al; an, an; ar, ar; as, as, as; at, at; ay, ay.