Template:Year article header/doc

These notes and instructions only appear to people reading the template directly; when it is used, you do not see this.

Instructions
The purpose of this template is to create a standard, uniform calendar description as the first sentence for all years from 1582 on with links to the appropriate terms. It's designed to say the year as either being "was" the year if it is before this year, "is" this year if it's the current year, and "will be" the year if it's after this year, e.g. in 2012, years 2011 and before would say "2011 was a common year starting on..." "2012 is the current year, and is a leap year starting on..." "2013 will be a common year starting on..."

Yes, it does know that only century years which are divisible by 400 are leap years.

Suppose that y is the current year. Then for year y+1, it will say "will be a", then in year y+1, it will say "is the current year, and is a", and finally in year y+2, it will say "was a".

The nice thing about this is that because it's all generated programmatically, when the current year changes it makes the change automatically without requiring human intervention.

Usage
  as the first item in the text of a year, e.g.   for the article for that year. Note that inserting the year directly as opposed to using was intentional; I needed to make calculations on the value passed and I wanted to make sure I could do that, plus I couldn't test the template if I used the PAGENAME parameter.

If not supplied an argument,   defaults its first parameter to.

Note to editors
It currently does work perfectly for years after 1582. Years before 1582 show Julian and prospective Gregorian. 1582 shows Julian plus warning and prospective Gregorian, 1583 and later, Gregorian with Julian and number of days off for years below 1924, Gregorian only after 1923.

Template data
{	"params": { "1": {			"label": "Year", "description": "The year to create an introduction for.", "example": "2018", "type": "number", "required": true }	},	"description": "This template creates an introduction to an article about a year." }