Help:Semantic Forms for selecting Categories

extension can be used for selecting multiple categories using a form, to do this you need to create two pages and you will probably want to enable the edit with form feature.

Form:Categories
The Form:Categories is used to generate the edit with form page and it places code like this into the page it is used to edit:

And this is the code to generate the multiple select form:

The Top_Category being the start of the category tree.

Template:Categories
The Template:Categories generates the category listing in the page:

From the code generated by the Form:Categories.

This is the code to transform the comma separated list of categories into the format needed to place the page into the categories: