The earliest form of manuscript Cyrillic, known as ustav, was based on Greek uncial script, augmented by ligatures and by letters from the Glagolitic alphabet for consonants not found in Greek. The Glagolitic alphabet was created by the monk Saint Cyril, possibly with the aid of his brother Saint Methodius, around 863. It was an adaptation designed to link the language of their mother, who was of Slavic origin, and their father, who was the Roman military commander of Thessaloniki, the second most important city of the Byzantine Empire. Cyrillic, on the other hand, was a creation of Cyril's students in the 890s at the Preslav Literary School as a more suitable script for church books, based on uncial Greek but retaining some Glagolitic letters for sounds not present in Greek. An alternative hypothesis proposes that it emerged in the border regions of Greek proselytization to the Slavs before it was codified and adapted by some systematizer among the Slavs; the oldest Cyrillic manuscripts look very similar to 9th and 10th century Greek uncial manuscripts, and the majority of uncial Cyrillic letters were identical to their Greek uncial counterparts. One possibility is that this systematization of Cyrillic was undertaken at the Council of Preslav in 893, when the Old Church Slavonic liturgy was adopted by the Bulgarian Empire. The Cyrillic alphabet was very well suited for the writing of Old Church Slavic, generally following a principle of "one letter for one significant sound", with some arbitrary or phonotactically-based exceptions. Particularly, this principle is violated by certain vowel letters, which represent plus the vowel if they are not preceded by a consonant. It is also violated by a significant failure to distinguish between /ji/ and /jĭ/ orthographically. There was no distinction of capital and lowercase letters, though manuscript letters were rendered larger for emphasis, or in various decorative initial and nameplate forms. Letters served as numerals as well as phonetic signs; the values of the numerals were directly borrowed from their Greek-letter analogues. Letters without Greek equivalents mostly had no numeral values, whereas one letter, koppa, had only a numeric value with no phonetic value. Since its creation, the Cyrillic script has adapted to changes in spoken language and developed regional variations to suit the features of national languages. It has been the subject of academic reforms and political decrees. Variations of the Cyrillic script are used to write languages throughout Eastern Europe and Asia. The form of the Russian alphabet underwent a change when Tsar Peter the Great introduced the Civil Script, in contrast to the prevailing Church Typeface, in 1708. Some letters and breathing marks which were used only for historical reasons were dropped. Medieval letterforms used in typesetting were harmonized with Latin typesetting practices, exchanging medieval forms for Baroque ones, and skipping the western European Renaissance developments. The reform subsequently influenced Cyrillic orthographies for most other languages. Today, the early orthography and typesetting standards remain in use only in Church Slavonic. A comprehensive repertoire of early Cyrillic characters has been included in the Unicode standard since version 5.1, published April 4, 2008. These characters and their distinctive letterforms are represented in specialized computer fonts for Slavistics.
Alphabet
In addition to the basic letters, there were a number of scribal variations, combining ligatures, and regionalisms used, all of which varied over time.
Numerals, diacritics and punctuation
Each letter had a numeric value also, inherited from the corresponding Greek letter. A titlo over a sequence of letters indicated their use as a number; usually this was accompanied by a dot on either side of the letter. In numerals, the ones place was to the left of the tens place, the reverse of the order used in modern Arabic numerals. Thousands are formed using a special symbol, , which was attached to the lower left corner of the numeral. Many fonts display this symbol incorrectly as being in line with the letters instead of subscripted below and to the left of them. Titlos were also used to form abbreviations, especially of nomina sacra; this was done by writing the first and last letter of the abbreviated word along with the word's grammatical endings, then placing a titlo above it. Later manuscripts made increasing use of a different style of abbreviation, in which some of the left-out letters were superscripted above the abbreviation and covered with a pokrytiediacritic. Several diacritics, adopted from Polytonic Greek orthography, were also used, but were seemingly redundant : Punctuation systems in early Cyrillic manuscripts were primitive: there was no space between words and no upper and lower case, and punctuation marks were used inconsistently in all manuscripts. Some of these marks are also used in Glagolitic script. Used only in modern texts
