Anno domini system of dating
Traditionally, English has copied Latin usage by placing the abbreviation before the year number for AD.
Since BC is not derived from Latin it is placed after the year number (for example: 68 BC, but AD 2011).
Alternatively, the secular abbreviations CE and BCE are used, respectively.
There is no year zero in this scheme, so the year AD 1 immediately follows the year 1 BC.
In this same history he also used another Latin term, "ante vero incarnationis dominicae tempus" ("the time before the Lord's true incarnation"), equivalent to the English "before Christ", to identify years before the first year of this era, even though he used zero in his computus.
Both Dionysius and Bede regarded Anno Domini as beginning at the incarnation of Jesus, but "the distinction between Incarnation and Nativity was not drawn until the late 9th century, when in some places the Incarnation epoch was identified with Christ's conception, i.e., the Annunciation on March 25" (Annunciation style).
Although the last non-imperial consul, Basilius, was appointed in 541 by Emperor Justinian I, later emperors through Constans II (641–668) were appointed consuls on the first 1 January after their accession.
All of these emperors, except Justinian, used imperial post-consular years for all of the years of their reign alongside their regnal years.
in 1505 for us) and on 12 April 1506, but not in 1505., and say that those who accept the story of the Massacre of the Innocents sometimes associate the star that led the Biblical Magi with the planetary conjunction of 15 September 7 BC or Halley's comet of 12 BC (less likely since comets were usually considered bad omens); even historians who do not accept the Massacre accept the birth under Herod as a tradition older than the written gospels.
"Anno an xpi nativitate" (before the birth of Christ) is found in 1474 in a work by a German monk.