This template is used on approximately 155,000 pages. To avoid major disruption and server load, any changes should be tested in the template's /sandboxor/testcases subpages, or in your own user subpage. The tested changes can be added to this page in a single edit. Consider discussing changes on the talk page before implementing them.
The templates P1 and P2 simply return the first respectively second unnamed input parameter respectively. For example:
{{P1|foo|bar|baz}} returns foo
{{P2|foo|bar|baz}} returns bar
These templates can be used inside other templates as an alternative to the {{#switch}} parser function, to switch between outputs based on whether the input is "1" or "2":
{{P{{{1}}}|output if 1|output if 2}}
Using {{#switch}}, this syntax is equivalent to
{{#switch:{{{1}}}|1=output if 1|2=output if 2}}
except that the parser function strips whitespace between parameters whereas the templates don't.
