The datatype Annotation URI is a variant of Type:URI. It is used in cases where a URI attribute needs to be exported as an owl:AnnotationProperty which is the case almost exclusively for imported attributes.

Intuitively, AnnotationProperties play a role that is similar to a comment or meta-property – something that does not have a direct meaning to the topic, but that may provide additional technical information. The type Annotation URI should thus be used very rarely. A typical example for its use is Property:see also which specifies the URI of an additional source of information on the subject.