Editing Template:Birth based on age as of date/doc

{{Documentation subpage}}
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{{Warning |''Do '''NOT''' use this template when the person is dead; consider {{tl|Birth based on age at death}} instead.''}}
{{High-use}}
{{Intricate template}}

For a person whose date of birth is unknown, this template estimates the person's birth year and current age based on a given age at a certain date. This is useful when a [[wp:reliable source|reliable source]] states only their age at the time of publication.

== Syntax ==
=== Typical use ===
<syntaxhighlight lang="wikitext"> {{birth based on age as of date | age | year | month | day }} </syntaxhighlight>
<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}<nowiki>}}</nowiki></code></div>
<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}}}
</div>
The age, year, and day must be supplied as [[natural number]]s; 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 only the publication year for a source is known, the "day" and "month" fields can be omitted.

=== No age ===
In some contexts—like the lead sentence of a biography—it may be desirable to show only the birth year, and not a person’s age. To suppress the age field, set {{para|noage|yes}}:
<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|noage=1|slash=y<nowiki>}}</nowiki></code></div>
<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|noage=1|slash=yes}}</div>

=== Separator ===
In general, the two possible birth years should be written out as: {{xt|1950 or 1951}}. In contexts which are tight for space, the separator between the two possible years should be a slash: {{xt|1950/1951}}. 

To use the <code>/</code> separator, add {{para|slash|yes}}.
<div style="margin-left:1.6em;">Code:</div>
<div style="margin-left:3.2em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|slash=yes<nowiki>}}</nowiki></code></div>
<div style="margin-left:1.6em;">Result:</div>
<div style="margin-left:3.2em;">{{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-2}}|{{#expr:12-{{CURRENTMONTH}}+1}}|{{CURRENTDAY}}|slash=yes}}</div>

== Examples ==
If, for example, a reference dated July 4, {{#expr:{{CURRENTYEAR}}-2}} mentions that someone is 50 years old, that person's birth year and age can be rendered using:
<div style="margin-left:1.6em;"><code><nowiki>{{birth based on age as of date|50|</nowiki>{{#expr:{{CURRENTYEAR}}-2}}|July|4}}</code></div>

{| class="plainlinksneverexpand" style="margin-top:0;"
!style="border:1px solid #aaa;background:#dfd;"|
The following examples are for a person reported as being 50 years old in {{#expr:{{CURRENTYEAR}}-1}}
|-
|
{{Aligned table
   |class=wikitable |colstyle=padding-right:1.0em;
   |col1style=font-family:monospace;padding-right:1.0em;
   |row1header=on| {{sans-serif|Template code}} | Result

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTH}}|{{CURRENTDAY}}}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTH}}|{{CURRENTDAY}}}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}|{{CURRENTDAY}}}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}|{{CURRENTDAY}}}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|noage{{=}}1}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12|31|noage=1}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|noage{{=}}1}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan|1|noage=1}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|{{CURRENTMONTHNAME}}}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|Jan}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}|12}}

   | {{braces|birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}}}
   |        {{birth based on age as of date|50|{{#expr:{{CURRENTYEAR}}-1}}}}
  }}
|}

{{Birth, death and age templates |BDA}}

<includeonly>{{Sandbox other|
| <!--PLEASE ADD CATEGORIES BELOW THIS LINE: -->
[[Category:Date mathematics templates]] 
}}</includeonly>
<templatedata>
{
	"params": {
		"1": {
			"label": "Age",
			"description": "Age of subject at date of reference's publication.",
			"example": "55",
			"type": "number",
			"required": true
		},
		"2": {
			"label": "Year",
			"description": "Year of publication of reference.",
			"example": "1950",
			"type": "number",
			"required": true
		},
		"3": {
			"label": "Month",
			"description": "Month of publication of reference.",
			"example": "8 or August",
			"type": "string",
			"suggested": true
		},
		"4": {
			"label": "Day",
			"description": "Day of publication of reference.",
			"example": "21",
			"type": "number",
			"suggested": true
		},
		"noage": {
			"label": "Hide age",
			"description": "Set to a value of 'yes' to display year of birth without the age",
			"example": "1",
			"type": "boolean",
			"default": "no (i.e., the default is to show the age)"
		},
		"slash": {
			"label": "Slash separator",
			"description": "Set to 'yes' to separate years with a '/' for tight spaces (e.g., table cells)",
			"suggestedvalues": [
				"yes"
			],
			"type": "boolean",
			"default": "no"
		}
	},
	"description": "This template calculates the birth year and current age based on the age as of a date.",
	"format": "inline",
	"paramOrder": [
		"1",
		"2",
		"3",
		"4",
		"noage",
		"slash"
	]
}
</templatedata>

==Redirects==
* [[Template:Bbad]]
* [[Template:Birth year from age as of date]]
* [[Template:Birth year from age at date]]