The Reference objects perform two functions: they connects factoids to either the historical persons or geographic locations involved in them. As the diagram below shows, all references are connected to assertions / factoids, and are either Person References, in which case they link to a Person, or they are Location References, in which case they link to a Location. A reference is connected to a particular spot in a source where a name for the person or place is written. Thus, both kinds can also have a property that records how the person or location’s name was recorded in the source at that point where they are mentioned for the factoid.
Subclassing of :PersonReference or :LocationReference is useful to establish different kinds of references. FPO uses subclassing for :PersonReference to specify the role of the person in the factoid. CCH/DDH projects have generally added further subclasses to :PersonReference or :LocationReference to define additional roles that interested them for persons or places in a factoid. For charter-oriented projects, for example, :PersonReference was further subclassed to allow the project to identify person as beneficiary and person as grantor.
- :Reference: In the factoid prosopography model, a :Reference item links an assertion / factoid to a person or a geographic location. As well as providing the link between the factoid and person, it also provides a place that can capture information about the particular spot in the source where the person or location is named, in particular how the name is written.
- :PersonReference: References that link to persons are :PersonReferences.
- :ReferenceAsObject: is a kind of Person Reference, and expresses a particular role for the individual: here the object (used in the RDF sense) of an assertion: e.g. For Edward in “Alfred was father of Edward the Elder.”
- :ReferenceAsSubject: is a kind of Person Reference, and expresses a particular role for the individual: here the subject (used in the RDF sense) of the assertion: e.g. For Alfred “Alfred was king”, or Alfred in “Alfred was father of Edward the Elder.”
- :LocationReference: References that link to geographic locations are :LocationReferences. Several CCH/DDH projects subclassed :LocationReference to allow them to specify a role for the geographic location in a factoid.
The main function of the :Reference is to connect factoids to persons or geographic locations. Thus, they primarily carry information in their relationships, described below. However, they also provide an object that represents a person or location in a particular factoid, and therefore in a particular spot in a particular text. Thus, they also have a property that allows the name, as it appears there, to be recorded.
- : hasNameInSourceAs for :Reference: provides a text string where the name for the person or geographic location, as it appears in the source, can be recorded. CCH/DDH project allowed only one name to be attached to each reference, and this has proven to be sufficient for all the projects.
The following relationship properties are defined in FPO for the :Reference set of classes:
- :hasReference (from :Assertion to :Reference): provides the path (via references) through which the person or persons associated with the assertion are defined, or geographic relationships are provided for an assertion / factoid. Note that CCH/DDH practice allowed more than one person to be linked to a single assertion / factoid, but each :Reference should have only on :hasReference link from a particular assertion / factoid.
- :references (from :PersonReference to :Person): :references is the mechanism used to link, through :Reference, a factoid to a person with which it is associated. Any number of :references statements (and therefore factoids) can be linked to a particular :Person, but CCH/DDH practice had each :PersonReference link only to one :Factoid and one :Person.
- :referencesLocation (from :LocationReference to :Location): :referencesLocation is the mechanism used to link, through a :LocationReference, a factoid to a geographic location with which it is associated. Any number of :referencesLocation statements (and therefore factoids) can be linked to a particular :Location, but CCH/DDH practice had each :LocationReference link to only one :Factoid and one :Location.