Abbreviations were often used to save space and effort when writing. They generally fall into three categories: suspensions, in which the end of a word is abbreviated, signalled by the use of a horizontal bar or another graphic symbol; contractions, in which another part of a word is abbreviated with the use of a graphic symbol; abbreviation symbols, used for whole words and often derived from the tachygraphic (shorthand) systems of ANTIQUITY (that of Tiro, Cicero's secretary, being most influential). All three types of abbreviation could be used in the same manuscript, as variable and invariable forms and as phonetic equivalents.
During Antiquity a few common elements were often abbreviated (notably the Latin word endings -bus and -que and the final m and n). These short forms are known as notae communes, while abbreviations for specialized jargon in legal texts are known as notae iuris. Abbreviations for nomina sacra ('sacred names'), such as the Greek xps form of Christus (see CHI-RHO), occur in EARLY CHRISTIAN works. INSULAR scribes were especially fond of abbreviations, including tironian notae, and Irish scribes used them extensively in order to produce pocket-size GOSPEL BOOKS for study purposes (pocket Gospels). With the growth of universities, from around 1200, the use of abbreviations proliferated. Medieval readers would have been familiar with such devices, although there were probably always some that were particularly obscure, and there is evidence that SCRIBES themselves sometimes puzzled over certain abbreviations.