Previous: 8.6. URI of an Item  

8.7. URI of non-document entities

The object of all discourses within the Akoma Ntoso framework can be described as a set of abstract classes and their instances and of the relationship among them. Cumulatively, definition of classes, relationships and instances are called an ontology.

The four most important classes of the Akoma Ntoso ontology are surely connected to documents,  Work, Expression and Manifestation, but many more exist, even if they are not connected directly to physical documents. The purpose of this section is to provide a syntax for non-document entities, i.e., instances of non-document classes, such as people, organizations, concepts, etc. Furthermore, the syntax described here can also be used for document entities as an equivalent syntax to the one specified in the previous sections.

Akoma Ntoso entities are always associated to a class, which provides a structure of properties and relationships to other instances of the same and other classes. Classes in the Akoma Ntoso ontology are organized in a complex maze of sub/superclasses. These are useful to give shape and meaning to a domain, and to provide structure to the overall set of instances of a base class. It is important to notice that sub/superclasses do not form necessarily a tree, but can form a more complex structure, namely a directed graph.

For instance, the class of Kenyan judges can be considered a sub class of both Kenyan persons and of persons whose job description is judge. That is, there is a (implicit or explicit) subclass of Judges and a (implicit or explicit) subclasses of Kenyans, both of which are in turn subclasses of Person, and Kenyan Judges is a subclass of both. In fact, we immediately derive the principle that every different value in every different property or relationship implicitly generates a class, that turns into an explicit class only because of our whim or need. For instance, the class of all persons named “Joe” exists implicitly, identifies all persons whose first name is “Joe”, and, if so desired, can be made explicit through the definition of a subclass of Person.

While this is very useful for determining relationships between entities, it affects interestingly the mechanism to associate URIs to such entities. In particular, there being no single hierarchy of classes, it is not appropriate to propose a single path of specifications from the super class to the final class. As such, ideally /person/judge/ke/JoeSmith must point to the same individual as /person/ke/judge/JoeSmith.

In order to maintain meaningfulness, permanence and invariance (which are the main requirements for our naming convention, as specified in the introduction of this document) we need to find a reliable naming mechanism for clearly identifying entities that does not depend on the sub/superclass organization except when strictly necessary.

In particular, we define the concept of Top Level Classes (TLC) that are guaranteed to be a partition of the overall domain of the Akoma Ntoso standard. TLC include Work, Expression, Manifestation, Item, Person, Organization, Concept, Object, Event and Place. The list of TLC may include in future more classes (e.g., Process, Role, Term, and more yet to be determined), as long as they keep on generating a partition (i.e., that they are disjoint and cumulatively describe all possible instance of the Akoma Ntoso domain). Members of the TLC classes can be subclassed at will and with no theoretical constraints.

Given the high number of foreseeable subclasses of the TLC, and the pointlessness of determining a fixed hierarchy in such number, the naming of entities should not depend on the presence or absence of a given class except for TLC. This means that it is necessary that each instance of each TLC is provided with an ID string that is guaranteed to be unique within the TLC. The syntax of this ID is dependent of the TLC class, and the syntax for each of the existing TLC is provided  in the next section.

Therefore, the URI for non-document entities consists of the following pieces:

• The base URL of a naming authority with URI-resolving capabilities
• A detail fragment organizing in a hierarchical fashion the additional data:
• The string “/ontology”
• The official name of the appropriate TLC
• Any number (including none) of slash-separated subclasses of the TLC, as long as they all refer to correct properties of the corresponding instance
• The ID of the instance, guaranteed to be unique within the TLC.

All components are separated by forward slashes (“/”) so as to exploit relative URIs in references.

• http://www.authority.org/ontology/person/ke.joe.smith.1964-12-22
  Joe Smith
  
  
• http://www.authority.org/ontology/person/ke/ke.joe.smith.1964-12-22
  Joe Smith (implying that he is a Kenyan)
  
  
• http://www.authority.org/ontology/person/ke/judge/ke.joe.smith.1964-12-22
  Joe Smith (implying that he is a Kenyan who is a judge)
  
  
• http://www.authority.org/ontology/person/judge/ke/ke.joe.smith.1964-12-22
  Joe Smith (implying that he is a judge who is a Kenyan)
  
  
• http://www.authority.org/ontology/person/kenyanjudge/ke.joe.smith.1964-12-22
  Joe Smith (implying that he is a Kenyan judge)
  
  

Please note that the classes Work, Expression, Manifestation and Item belong to the ontology as much as the other classes. As such, each Work, Expression and Manifestation can also be indicated with an ontology-based URI that refers to exactly the same entity.

Therefore, the following URIs are equivalent pair-wise, and refer to the same entities:

• http://www.authority.org/sl/act/2004-02-13/2
  http://www.authority.org/ontology/work/sle.act.2004-02-13.2
  
  
• http://www.authority.org/sl/act/2004-02-13/2/eng@2004-07-21
  http://www.authority.org/ontology/expression/sle.act.2004-02-13.2.eng@2004-07-21
  
  
• http://www.authority.org/sl/act/2004-02-13/2/eng@2004-07-21/main/schedule1
  http://www.authority.org/ontology/expression.component/sle.act.2004-02-13.2.eng@2004-07-21.main.
  schedule1
  
  
• http://www.authority.org/sl/act/2004-02-13/2/eng@2004-07-21/main.akn
  http://www.authority.org/ontology/manifestation/sle.act.2004-02-13.2.eng@2004-07-21.main.akn
  
  

The IDs for Top Level Classes

As mentioned in the previous section, the hierarchy of path elements is of no use for identifying instances of each TLC, given the fact that there can be no unique hierarchy of subclasses in the Akoma Ntoso ontology.

Thus each instance of the ontology needs to be provided with an ID guaranteed to be unique within the TLC it belongs to. The syntax of the ID depends on the actual TLC, and is briefly explained in the following schema.

TLC Person

A dot-separated string composed of the country of citizenship, the first name, the family name, the birth date in yyyy-mm-dd format, and an optional arbitrary string if ambiguity exists (e.g., if two individuals with the same name and the same birth date exist in the same country).

• ke.joe.smith.1964-12-22
  Mr. Joe Smith, the only Kenyan citizen with that name born on December 22nd, 1964
  
  

TLC Organization

A dot-separated string composed of the country of registration (or the string “int” if international, or the string “unreg” if not registered anywhere), a recognizable form of the organization name and an optional arbitrary string if ambiguity exists (e.g., if two organizations with the same name exist in the same country).

• ke.parliament
  the Kenyan Parliament
  
  

TLC Concept

A unique form of the terms specifying the concept joined with dots. No country specifications are necessary for concepts

• Presidential.election
  the concept of Presidential Election
  
  

TLC Object

T.B.D.

TLC Event

T.B.D.

TLC Place

T.B.D.

TLC Process

T.B.D.

TLC Role

T.B.D.

TLC Term

T.B.D.

TLC Work

The domain-less URI of the work as specified in this document, with all slash substituted by dots.

• sl.act.2004-02-13.2
  Sierra Leone enacted Legislation. Act number 2 of 2004.
  
  

The domain-less URI of the work as specified in this document, with all slash substituted by dots.

• sl.act.2004-02-13.2.en@2004-07-21
  Sierra Leone enacted Legislation. Act number 2 of 2004.  English version, as amended on July 2004
  
  

The domain-less URI of the work as specified in this document, with all slash substituted by dots.

• sl.act.2004-02-13.2.en@2004-07-21.schedule01
  Attachment “schedule01” of Sierra Leone enacted Legislation. Act number 2 of 2004.  English version, as amended on July 2004
  
  

The domain-less URI of the work as specified in this document, with all slash substituted by dots.

• sl.act.2004-02-13.2.en@2004-07-21.akn
  Package of all documents including XML versions of the Sierra Leone enacted Legislation. Act number 2 of 2004.  English version, as amended in July 2004
  
  

T.B.D.

TLC Item

T.B.D.

Previous: 8.6. URI of an Item