This is the {{category handler/numbered}} sub-template.

Do not use this template directly, use {{category handler}} instead. This template is called from {{category handler}}, see user documentation there.

The rest of the sections here are only for those that want to understand the internal workings of this template.

This sub-template makes it possible for its parent-template to take input in two forms:

{{category handler
| 1 = Input
| main = 1
| talk = 1   <!--Reusing "Input" for both the main and talk parameters-->
}}

{{category handler
| main = Input1
| talk = Input2   <!--Instead feeding text directly to the talk parameter-->
}}

This sub-template takes a bunch of numbered parameters. There's no limit to the number of parameters it can use, other than what the servers and MediaWiki system can handle.

It also takes a parameter named data. If data is a number, then it returns the data of the corresponding numbered parameter. If data is something else, for instance a category name, then it returns data unchanged.

Here's how you would normally call this sub-template:

{{category handler/numbered
| 1 = {{{1|}}}
| 2 = {{{2|}}}
| 3 = {{{3|}}}
| 4 = {{{4|}}}
| data = Input can be a number between 1-4, or something else.
}}

In the above example, since the parent-template feeds only 1-4, then only the numbers 1-4 will work properly. Feeding other numbers will return an empty string.

• mw:Help:Extension:ParserFunctions – About {{#iferror:||}} etc.