What is "indiction"

Indiction \In*dic"tion\, n. [L. indictio: cf. F. indiction. See Indict, Indite.]

1. Declaration; proclamation; public notice or appointment. [Obs.] ``Indiction of a war.''
   --Bacon.

   Secular princes did use to indict, or permit the indiction of, synods of bishops.
   --Jer. Taylor.

2. A cycle of fifteen years.

   Note: This mode of reckoning time is said to have been introduced by Constantine the Great, in connection with the payment of tribute. It was adopted at various times by the Greek emperors of Constantinople, the popes, and the parliaments of France. Through the influence of the popes, it was extensively used in the ecclesiastical chronology of the Middle Ages. The number of indictions was reckoned at first from 312 a. d., but since the twelfth century it has been reckoned from the birth of Christ. The papal indiction is the only one ever used at the present day. To find the indiction and year of the indiction by the first method, subtract 312 from the given year a. d., and divide by 15; by the second method, add 3 to the given year a. d., and the divide by 15. In either case, the quotient is the number of the current indiction, and the remainder the year of the indiction. See Cycle of indiction, under Cycle.

late 14c., "period of fifteen years," a chronological unit of the Romans, originally for taxation purposes, fixed by Constantine and reckoned from Sept. 1, 312; it was still in use in the Middle Ages. From Latin indictionem (nominative indictio) "declaration, appointment," noun of action from past participle stem of indicere (see indictive).

n. 1 (context historical English) A fiscal period of fifteen years, instituted by http://en.wikipedia.org/wiki/Constantine in 313 (C.E.) (but counting from 1st September 312), used throughout the Middle Ages as a way of dating events, documents etc. 2 A declaration or official announcement. 3 (context historical English) The decree made by Roman Emperors which fixed the property tax for the next fifteen years.

n. a 15-year cycle used as a chronological unit in ancient Rome and adopted in some medieval kingdoms

An indiction is any of the years in a 15-year cycle used to date medieval documents throughout Europe, both East and West. Each year of a cycle was numbered: first indiction, second indiction, etc. However, the cycles were not numbered, thus other information is needed to identify the specific year.

When the term began to be used, it referred only to the full cycle, and individual years were referred to as being Year 1 of the indiction, Year 2 of the indiction, etc. But usage changed, and it gradually became common to talk of the 1st indiction, the 2nd indiction, and so on.

Indictions originally referred to the periodic reassessment for an agricultural or land tax in late third-century Roman Egypt. These were originally in 5-year cycles beginning in 287 AD, then in a non-cyclic series which reached number 26 by 318 AD. But by 314 AD, the 15-year cycle had appeared. The Chronicon Paschale (c. 630 AD) assigned its first year to 312–313 AD, whereas a Coptic document of 933 AD assigned its first year to 297–298 AD, one cycle earlier. Both of these were years of the Alexandrian calendar whose first day was Thoth 1 on August 29 in years preceding common Julian years and August 30 in years preceding leap years, hence each straddled two Julian years.

The indiction was first used to date documents unrelated to tax collection in the mid-fourth century. By the late fourth century it was being used to date documents throughout the Mediterranean. In the Eastern Roman Empire outside of Egypt, the first day of its year was September 23, the birthday of Augustus. During the last half of the fifth century, probably 462 AD, this shifted to September 1, where it remained throughout the rest of the Byzantine Empire. In 537 AD, Justinian decreed that all dates must include the indiction via , which eventually caused the Byzantine year to begin on . But in the western Mediterranean, its first day was according to Bede, or the following or , called the papal indiction. An indictio Senensis beginning is sometimes mentioned.

The 7,980-year Julian Period was formed by multiplying the 15-year indiction cycle, the 28-year solar cycle and the 19-year Metonic cycle.

The indiction for a modern Anno Domini year Y (January 1 to December 31) is

For example, the indiction for the year 2011 is 4

So 2008, three years earlier, was a first indiction

This applies even when the Anno Domini year begins during the preceding September, as it did during the early Middle Ages.

The indiction for a Byzantine AM year (beginning September 1) is found by dividing that year number by 15 and taking the remainder ( modulus). If the remainder is zero, then the indiction is 15. For example, the Byzantine year AM 6961, when Constantinople fell to the Ottoman Turks, is indiction 1