Fyrimynd:Birth based on age as of date/doc

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This template calculates the birth year and current age based on the age as of a date. This is useful when a reference states only their age at the time of the reference's publication.

Syntax

 {{birth based on age as of date |age |year|month|day}}

The age, year, and day must be supplied as natural numbers; month can be specified as a natural number as well as by name or abbreviation (e.g. "August" or "Aug"). The Gregorian calendar is assumed, with no special support provided for dual dating or the difference between Old Style and New Style dates.

If they are not known, the "day" and "month" fields can be omitted; this is useful if, for example, only the publication year for a source is known.

Options

To suppress the age field:

 {{birth based on age as of date |age |year|month|day |noage=1}}

With the "noage=1" option, the month and day can be "1".

Examples

If, for example, a reference dated July 4, 2023 mentions that someone is 50 years old, that person's birth year and age can be rendered using:

{{birth based on age as of date |50 |2023|July|4}}

The following examples are for a person reported as being 50 years old in 2023

Template code	Result
{{birth based on age as of date 50 2023 12 26}}	1972/1973 (age 51)
{{birth based on age as of date 50 2023 desember 26}}	1972/1973 (age Feilur í málbering: Óvæntaður < operatorur.–Feilur í málbering: Óvæntaður < operatorur.)
{{birth based on age as of date 50 2023 12 31}}	1972/1973 (age 50–51)
{{birth based on age as of date 50 2023 Jan 1}}	1972/1973 (age 51–52)
{{birth based on age as of date 50 2023 12 31 noage=1}}	1972/1973
{{birth based on age as of date 50 2023 Jan 1 noage=1}}	1972/1973
{{birth based on age as of date 50 2023 desember}}	1972/1973 (age Feilur í málbering: Óvæntaður < operatorur.–Feilur í málbering: Óvæntaður < operatorur.)
{{birth based on age as of date 50 2023 Jan}}	1972/1973 (age 51–52)
{{birth based on age as of date 50 2023 12}}	1972/1973 (age 50–52)
{{birth based on age as of date 50 2023}}	1972/1973 (age 50–52)