Is it possible to create a Category (e.g. manually) in the database, which is NOT taken in account ,when alle the static pages are created? (Exspecially the first page with the category overview.

I would like to exclude (only) one Category from this start page. Entrys in that category should only be found, when using the search tool.

Has anyone an idea, where I have to look at in order to realize that?

One way to do this would be to add a column to the Category table that specifies whether or not to show that category, and then change the pages that show the category to check for that column before showing it. Or if it's just a few categories that you want to hide, then just check for those specific category ID's in the template (eg. <%if ID != 23 and ID != 36%><%include subcategory.html%><%endif%>).

Adrian