An ontology describing the concept of a tagging Denotes the visibility of a Tagging. Can be one of {Private Public Protected}. The application using this ontology has to take care of handling the authentication etc. Visibility any foaf:Person or foaf:Group who has at least one tagging is a Tagger. Tagger Tag represents a single tag or keyword. Each tag has a unique URI. Equal tags (e.g. "san francisco" and "san fran") can be semantically related via the sameTag property. Semantic relations, such as broader and narrower terms (e.g. "blue" is kind of "color"), can be expressed with the SKOS core ontology (e.g. http://www.w3.org/2004/02/skos/core#broader). Therefore Tag is a subclass of SKOS core Concept. Denotes the concept of a tagging: a Tagging consists of at least the basic tuple {tagger, resource, tags}. All other properties are optional. Furthermore Tagging follows the ValuePartition pattern, which means that it can only have values from either PublicTagging, PrivateTagging or ProtectedTagging. Tagging the domain (or even community) in which the tagging occured (e.g. delicious, flickr). specifiying a domain allows for cross-application tagging without losing the context in which the tagging has been done. Service Domain taggedResource specifies the resource being tagged type of the resource, e.g. image, text, ... this should be decided from the system (e.g. based on the MIME type), not from the user. thus, a tagged resource can have only one type. type specifies the tag that belongs to the tagging. Each tagging can have multiple tags tag domain specifies that a tagging happens in the context of a specific domain (i.e. flickr, delicious). a tagging can also belong to multiple domains (e.g. multiple social bookmarking tools), which allows for cross-application tagging. denotes the visibility of the tagging (Private, Public or Protected) Visibility the homepage URI of a ServiceDomain (i.e. a service which allows for tagging resources). service homepage tag name denotes the name (displayname) of a tag. A Tag can have multiple tag names which include variations of the same name (i.e. "c++", "cplusplus", "c_plus_plus",...). Thus one can infer that they all denote the same tag. additional notes to be added to a tagging (e.g. "picture of my cat mauzi") Notes date specifies the date and time of the tagging Service Name denotes the name of a tagging service provider, e.g. flickR denotes equality between two tags with different URIs. if a tag has multiple name, then you should provide a preferred name, which will be displayed. If a Tag has only one tagName, then prefTagName should have the same value. has Tagging relates a Tagger to his Taggings.