Yi, an abbreviation for the IEEE prefix yobi which represents 2
This page disambiguates a two-character combination which might be any or all of: an abbreviation, an acronym, an initialism, a word in English, or a word in another language.
The theory is supported by the fact that the Cyrillic alphabet almost completely replaced the Glagolitic in northeastern Bulgaria as early as the end of the tenth century, whereas the Ohrid Literary School—where Saint Clement worked—continued to use the Glagolitic until the twelfth century.
Although Cyril is almost certainly not the author of the Cyrillic alphabet, his contributions to the Glagolitic and hence to the Cyrillic alphabet are still recognised, as the latter is named after him.
Cyrillic uppercase and lowercase letter-forms are not as differentiated as in Latin typography.