Editing Template:Category handler/doc (section)

=== The "category2" parameter ===

For backwards compatibility this template kind of supports the old "category =" parameter. But the parameter name "category" is already used in this template to feed category data for when in category space. So instead this template uses '''category2''' for the usage similar to '''nocat'''. Like this:

* If "<code>category2 =</code>" (empty but defined), or "<code>category2 = no</code>", or if '''category2''' is fed any other data (except as described in the next two points), then this template does ''not'' categorize.
* If '''category2''' is undefined or if "<code>category2 = ¬</code>", then this template categorizes as usual.
* If "<code>category2 = yes</code>" this template categorizes even when on blacklisted pages.

When adding this template to a template that already uses the "<code>category =</code>" logic, then you can do like this to not break any existing usage:

<pre>
{{category handler
| [[Category:Somecat]]
| nocat = {{{nocat|}}}   <!--So "nocat=true/false" works-->
| category2 = {{{category|¬}}}   <!--So "category =" works-->
}}
</pre>

Note that the "<code>¬</code>" is necessary, it helps this template to detect if the '''category''' parameter is defined but empty, or undefined.