Conceptual Model Diagrams

Relevant Information

The figure below provides a general view of the Classes and relations of the ePO v2.0.1 Ontology. As well as the previous version, this version focuses on e-Notification and e-Access.

Figure 1. Legend
  • Boxes in colour beige are Classes, i.e. main entities of the ontology, like "Procurement Procedure", "Procuring Entity", "Economic Operator", etc.;

  • Boxes in colour green are "Code Lists", i.e. enumerations of disjoint concepts represented with a code);

    • Classes may contain codes. In this representation, the ePO codes are not included inside the Class but are represented as associations of the Class to a specific enumeration element. The name of the code is built upon the verb "uses" and the name of the enumeration. Thus the triple used to say that a Procurement Procedure is of type Open is expressed like this in the OWL-TTL:

      • :ProcurementProcedure :usesProcurementProcedureType at-voc:ProcurementProcedureType, where : is the default prefix representing the ePO ontology and at-voc: is the prefix reserved for the namespace representing all the codes defined in ePO (eProcurement-specific, to be located on EU Vocabularies).

  • Classes associate other classes via "object properties", i.e. directed association arrows ("predicates", from the ontology perspective) that have a class at the origin (the subject of a triple, in the ontology) and another class at the end of the link (the "object" of the triple).

  • "Data properties", i.e. links between the Class and more primitive/basic elements, are represented as attributes of the Classes, e.g. Text, Indicator, Date, etc.;

    • Data properties define what kind of value the attributes of the classes should have. For example, the class "Procurement Project" has three attributes: Description, ID and Title. Each attribute has one type of data assigned. The descriptions and titles should be expressed as a Text, and the ID should be an Identifier.

  • Associations between Classes are represented as unidirectional arrows to keep the diagrams simple. However, when the association is bi-directional it is indicated with two predicates and the second one is enclosed with parenthesis "()". In the OWL-TTL these are declared as "inverse" properties. Examples: "Procurement Procedure includes lots (belongs to) Lots", in the diagram, is to be read as:

    • "Procurement Procedure includes one or more Lots", and

    • "One Lot belongs to one Procurement Procedure".