Scribal abbreviation by "contraction" and was mostly a Christian usage for sacred words, Nomina Sacra; non-Christian sigla usage usually limited the number of letters the abbreviation comprised and omitted no intermediate letter. One practice was rendering an overused, formulaic phrase only as a siglum: DM for "Dis Manibus" ("Dedicated to the Manes"); IHS from the first three letters of "ΙΗΣΟΥΣ"; and RIP for "requiescat in pace" ("Rest in Peace") because the long-form written usage of the abbreviated phrase, by itself, was rare. According to Trabe, these abbreviations are not really meant to lighten the burden of the scribe but rather to shroud
Common Era "before the beginning of the vulgar æra, by which we now compute the years from his incarnation." A 1796 book uses the term "vulgar era of the nativity". The first so-far-discovered usage of "Christian Era" is as the Latin phrase "aerae christianae" on the title page of a 1584 theology book. In 1649, the Latin phrase "æræ Christianæ" appeared in the title of an English almanac. A 1652 ephemeris is the first instance so-far-found for English usage of "Christian Era". The English phrase "common Era" appears at least as early as 1708, and in a 1715 book on astronomy is