There are templates that should only be used in one namespace or a limited number of namespaces. If those templates are used in other namespaces, then they will likely populate this category. Many templates use the "demo" or "nocat" parameters to allow usage in other namespaces.

Some templates may only be used in one or two namespaces, while others may be used in any namespace. Still others can be used in all but one namespace. An rcat's template documentation is required to show if there are any namespace limitations.

If any template is used in the wrong namespace, then instead of populating the appropriate category, it may populate this category. Be sure to have your User Preferences – Advanced options set to "Show hidden categories". Most templates place the pages that use them into hidden categories, like this one, and you will not be able to see the hidden categories on redirect pages until you set your preferences to "show" them.