tag-scheme

Contains the scheme (that is URI) of a tag structure that may be used to tag content items of the type represented by this element's parent content-type element. Client applications such as CUE can use the presence of tag-scheme elements to determine which tags they make available to users editing content items. CUE does not display a Tags tab for content types that have no tag-scheme elements.

Syntax
<tag-scheme>
  text
</tag-scheme>