11th October 2011, 02:09 PM

Found this in the 'notes for contributors' for RADIOCARBON

Calibrated Ages: cal BC, cal AD, cal BP

The symbol cal is used to express calibrated radiocarbon ages. Note that ?cal? should be understood as ?calibrated?, not ?calendar?. A ?calendar age? is an absolute date, whether known or guessed; a ?calibrated date? is an estimate based on statistical probability, and is therefore properly expressed as one or more ranges of calendar years, accompanied by the appropriate confidence level.

Wrong: The linen sample dated to 780 ? 40 BP, or cal AD 1263

Correct: The linen sample dated to 780 ? 40 BP, or cal AD 1220?1281 (1[FONT="]σ[/FONT])

Correct: The linen sample dated to 780 ? 40 BP, or cal AD 1220 (1263) 1281 (1[FONT="]σ[/FONT])

In this example, AD 1263 is the intercept of 780 BP on the dendrochronological calibration curve; it is nota calendar equivalent of a conventional 14C age. The first correct form expresses a calibrated date range at the 1-sigma confidence level; the second form gives the end points of the 1-sigma range with the intercept year in parentheses.

There are several valid ways to express calibrated dates; see Stuiver and Pearson (1993, p 5?6) and Stuiver and Reimer (1998, Section 4) for technical details. The method(s) chosen to represent cal dates should always be explicitly mentioned when the dates are presented.

RADIOCARBON Instructions for Authors 7 22 August 2005

Some in the radiocarbon community object to the term cal BP because they feel that BP is properly reserved for conventional radiocarbon ages, which yield BC/AD date ranges when calibrated. However, cal BP is widely used in the literature and has the advantage of providing a scale that does not break at AD 1 / 1 BC. A date expressed as ?N cal BP? is equivalent to the date (AD 1950 ? N years).

Seems both BP or BC/AD are technically correct

Calibrated Ages: cal BC, cal AD, cal BP

The symbol cal is used to express calibrated radiocarbon ages. Note that ?cal? should be understood as ?calibrated?, not ?calendar?. A ?calendar age? is an absolute date, whether known or guessed; a ?calibrated date? is an estimate based on statistical probability, and is therefore properly expressed as one or more ranges of calendar years, accompanied by the appropriate confidence level.

Wrong: The linen sample dated to 780 ? 40 BP, or cal AD 1263

Correct: The linen sample dated to 780 ? 40 BP, or cal AD 1220?1281 (1[FONT="]σ[/FONT])

Correct: The linen sample dated to 780 ? 40 BP, or cal AD 1220 (1263) 1281 (1[FONT="]σ[/FONT])

In this example, AD 1263 is the intercept of 780 BP on the dendrochronological calibration curve; it is nota calendar equivalent of a conventional 14C age. The first correct form expresses a calibrated date range at the 1-sigma confidence level; the second form gives the end points of the 1-sigma range with the intercept year in parentheses.

There are several valid ways to express calibrated dates; see Stuiver and Pearson (1993, p 5?6) and Stuiver and Reimer (1998, Section 4) for technical details. The method(s) chosen to represent cal dates should always be explicitly mentioned when the dates are presented.

RADIOCARBON Instructions for Authors 7 22 August 2005

Some in the radiocarbon community object to the term cal BP because they feel that BP is properly reserved for conventional radiocarbon ages, which yield BC/AD date ranges when calibrated. However, cal BP is widely used in the literature and has the advantage of providing a scale that does not break at AD 1 / 1 BC. A date expressed as ?N cal BP? is equivalent to the date (AD 1950 ? N years).

Seems both BP or BC/AD are technically correct