View source for Conjectural dates in MARC records

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This article provides guidance for graphic materials and manuscript catalogers using DCRM(G) and DCRM(MSS) respectively. Catalogers using DCRM(B) or RDA should consult those standards instead (or copy it all here, and update this introduction).

==General information==
The patterns for supplying a conjectural date given here follow DCRM(MSS) by omitting square brackets and spelling out "circa". When cataloging accord to DCRM(G), catalogers should open and close the date are with square brackets, and use the abbreviation "ca."

Examples of MARC coding for "circa" dates derive from ''Cataloging Cultural Objects'' (CCO), which provides instructions for both eye-readable and machine-readable dates when cataloging. For example, machine-readable "circa" dates give an eleven year range: five years before and five years after the specified year.

In OCLC Connexion: enter Date type in the "DtSt" fixed field; enter Date 1 and Date 2 in the "Dates" fixed field.

In Voyager: use the "008" dialog box to enter Date type in "Publication Status", Date 1 in "Date 1 (yyyy)", and Date 2 in "Date 2 (yyyy)" keeping in mind that Date 2 for material with month and day will be entered as mmdd, not yyyy.

==Examples with MARC coding==

Keep in mind that "q" only applies to uncertain dates that use both Date 1 and Date 2 fields, not to uncertainty in general. It tells the system to look at the next 8 characters for date information, not just the next four characters.

{| class="wikitable"
|-
! Variable text !! Meaning !! Date type !! Date 1 !! Date 2
|-
| 1845? January 11|| year probable, month and day certain || e || 1845 || 0111
|-
| 1560? || probable year || s || 1560 || ____
|-
| circa 1580 || approximate year || q || 1575 || 1585
|-
| circa 1580? || probable approximate year || q || 1575|| 1585
|-
| 1814 or 1815 || one year or the other || q || 1814 || 1815
|-
| between 1618 and 1648 || span certain|| q|| 1618|| 1648
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|-
| Example || Example || Example || Example || Example
|}

==Additional instructions==
Avoid using "not before..." and "not after..." on their own in catalog records (but go ahead in exhibition labels and other situations where the general era will be evident from the surrounding context). Instead, aways provide a best guess (e.g., "between 1600? and not after 1687"). It looks awkward, but it makes meaningful date filtering and sorting possible because the machine-readable date will be something more specific than "uuuu" (in means "any year between 1 CE and 9999 CE" for years in the Common Era, and any year between the beginning of time and 1 BCE for years before the Common Era).

[[Category:Cataloging]]
[[Category:Staff policies and procedures]]
[[Category:MARC]]