Format for Period Fields

Period fields allow you to enter a date or range of dates in a wide array of formats, all of which can be organised and understood by a computer. This allows Calm to be able to sort date ranges or an approximate dates the same way it would an exact date.

Various basic elements (like a year, a season, or a decade) can be used to describe a period. They can be used either singularly or combined to build up a date or date range. In addition, various qualifiers (like ‘c.’ for circa or ‘early’ for a century) can be applied to these elements. For example, a date field could be as simple as ‘1899’ or as complex as ‘c. spring 1743-3rd Jan 1788’ using these elements.

All dates in period fields are assumed to be on the Western (Gregorian) calendar, regardless of your local settings.

Text is not case sensitive and punctuation is ignored.

Table of Elements

Table of Qualifiers

Table of Valid Formats

Table of Elements

The following elements make up formats valid for period fields (remember that period fields ignore punctuation and capitalisation, so n.d. and ND are equally valid ways of indicating no date):

Element	Type in…	Example	How Calm Interprets the Date
century	A number divisible by 100 followed by 's' or an ordinal number followed by the word 'century' or 'cent.'	1900s, 1800s, 12th cent., 12th Century, 12th cent	= 1 January of the year ending in 00 to December 31 of the year ending in 99 (e.g. 1900-1999)
decade	A number divisible by 10 followed by 's'¹	1910s, 720s	= 1 January of the year ending in 0 to 31 December of the year ending in 9 (e.g. 1910-1919)
month	A month’s name, using either a 3-letter abbreviation or the full name	Jan, Feb, Jul, Sep, December	= First day of the month to last day of the month
year	A number over 31 (or a number under 31 followed by B.C./B.C.E./A.D./C.E.)	1910, 622, 4 B.C.	= 1 January of the year to 31 December of the year
number	A two-digit number under 32 (usually used to indicate a day)	21 Jan, 12 century	= It depends on the context
ordinal	A number expressed as a word or a number with a -st, -nd, -rd, -th suffix²	Twenty-first, 11th	= The date mentioned
no date	'n.d.' or 'undated'	undated, N.D.	= An empty field
present	The word 'present'	present	= The date the record was saved. When a re-index takes place, it will then be understood as the date of the re-index
season	spring, summer, autumn, fall, winter	spring 1918	= Spring: March-May, summer: June-August, autumn/fall: September-November, winter: December-February
law terms	Michaelmas, Hilary, Easter, Trinity	Hilary 1963	= Michaelmas: October-November, Hilary: January-February, Easter: April-May, Trinity: June-July

¹ The first decade of a century (e.g. 1900s) will always be interpreted by Calm as referring to the full century. Therefore, to indicate the decade, you must write 1900-1909.

² The ordinal element must be used with both parts of a range. 15th-27th Jan 1987 is acceptable, but not 15-27th Jan 1987.

Table of Qualifiers

The following qualifiers may be added to a date range (remember that period fields ignore punctuation and capitalisation, so a.d. and AD are equally valid ways of indicating anno Domini):

Qualifier	How Calm Interprets the Date
pre	= up to 10 years before
post	= up to 10 years after
early (in a century)	= 00 to 39 (e.g., 1900-1939)
mid., middle (of a century)	= 30 to 69 (e.g., 1930-1969)
late (in a century)	= 60 to 99 (e.g., 1960-1999)
about, approx., c., circ., circa	= the year and 10 years either side
between	= no change¹
fl., floruit	= no change¹
[gaps]	= no change¹
A.D., C.E.	= year in ascending order following 1 B.C.²
B.C., B.C.E.	= year in descending order prior to 1 A.D.
to, x	= from date before qualifier to date after qualifier

¹ These qualifiers can be included because they are meaningful to people reading the date, but will be ignored by Calm when sorting it.

² A.D./C.E. is only necessary for the years 1-31 (this stops them being confused with days). All other years are assumed to be A.D./C.E. unless noted otherwise.

Table of Valid Formats

Valid date formats include:

Elements	Example
century	1900s
century century	1800s-1900s
decade	1910s
decade decade	1910s-1920s
month month year	Jan-May 1999
month year	April 1456
month year month year	January 1256-February 2002
month year number month year	Jan 1689-23 December 2001
month year ordinal month year	Jan 1689-23rd December 2001
number century	late 13 century
number number year¹	13/6/1278
number number year number number year	13/01/1245-23/08/1678
number month number month year	12 Dec-16 Dec 1435
number month year	15 Jul 1678
number month number month year	13 Jun-15 December 1778
number month year	13 Aug 1787
number month year month year	14 Sep 1357-Jan 1367
number month year number month year	23 Apr 1278-28 Feb 1456
number month year year	23 Jan 1300-1301
number number century	12-13 century
number number month year	23-27 Jan 1987
year month number	1974 Nov 30
ordinal century	early 12th century
ordinal century ordinal century	12th century-mid 20th century
ordinal month ordinal month year	29th Oct-30th Oct 2002
ordinal month year	10th Dec 2002 A.D.
ordinal month year number month year	11th Jan 1899-12 Dec 1999
ordinal month year ordinal month year	23rd Dec 1233-23rd Mar 1733
ordinal month year year	13th Jul 1456-1789
ordinal number year	23rd 12 1899
ordinal number year ordinal number year	23rd 12 1899-13th 2 1999
ordinal ordinal century	12th-16th cent.
ordinal ordinal month year	12th-13th Dec 1678
year	1456
year month	1974 Nov
year month month	1974 Nov-Dec
year month month number	1982 Sep-Nov 01
year month year month	1974 Nov-1975 Dec
year month year month number	1974 Nov-1975 Dec 31
year month number month	1974 Nov 01-Dec
year month number month number	1974 Nov 01-Dec 31
year month number number	1974 Nov 01-30
year month number year	1970 Mar 01-1990
year month number year month number	1974 Nov 01-1975 Dec 31
year year month	1974-1975 Nov
year year month number	1974-1975 Nov 30
year ordinal century	1256-15th century
ordinal century year	16th century-1704
year year	1789-1867
season year	spring 1918
season year season year	spring 1918-summer 1920
law term year	Easter 1916
law term year law term year	Hilary 1966-Trinity 1974

¹ Unlike dates in date type fields, which appear in the form of Day-Month-Year or Month-Day-Year depending on your system’s date settings in Windows, this is always interpreted by Calm as Day-Month-Year.