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.
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Boxes in colour beige are Classes, i.e. main entities of the ontology, like "Procurement Procedure", "Procuring Entity", "Economic Operator", etc.;
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Boxes in colour green are "Code Lists", i.e. enumerations of disjoint concepts represented with a code);
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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:
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: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).
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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).
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"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.;
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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.
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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:
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"Procurement Procedure includes one or more Lots", and
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"One Lot belongs to one Procurement Procedure".
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