From Fallen London Wiki
Template documentation (for the above template, sometimes hidden or invisible)

This template adds banners depending on whether certain Semantic MediaWiki properties are set.

In particular, it displays {{HasGuide}} if there is a {{GuideFor}} template on the respective guide page and this page is in the list passed to {{GuideFor}}. Therefore, if you wish to change whether the {{HasGuide}} appears on a given page, but you cannot find it in the source code of the article, you have to edit the guide page and remove the article from the list.

Visit Template:SMWBanners/doc to edit this text! (How does this work?)