eProcurement Ontology overview


In 2016 the Publications Office of the European Union (Publications Office or OP) started a project funded by the ISA Programme to organise and support the development of a Public Procurement Ontology (ePO).

The ultimate objective of the ontology is to put forth a commonly agreed OWL ontology that will conceptualise, formally encode and make available in an open, structured and machine-readable format data about public procurement, covering it from end to end, i.e. from notification, through tendering to awarding, ordering, invoicing and payment. With this goal in mind the OP engaged a Working Group (WG) of experts with the mission of building consensus on the analysis results and deliverables developed by the OP’s teams.

By mid-2017 a version 1.00 of the Ontology was delivered and submitted to the Working group for discussion. All the materials related to this version were made public and are accessible through the ISA2 Joinup platform; including the discussions held in the Working Group (WG).

A new stage of the development, identified as ePO v2.0.0, was initiated in January 2018. The goal of this new version is to improve and extend the previous version.

This document describes the objectives, the methodological approach and the deliverables produced in this new version.


Given the increasing importance of data standards for e-Procurement, a number of initiatives driven by the public sector, the industry and academia have been launched in the recent years. Some have grown organically, while others are the result of standardisation work. The vocabularies and the semantics that they are introducing, the phases of public procurement they are covering, and the technologies they are using vary greatly amongst themselves. These differences hamper data interoperability and their reuse.

This situation creates the need for a common representation of the knowledge about the eProcurement domain as it is understood and practiced in the European Union. For this to happen a common vocabulary, axioms and rules are needed.

This document describes the work carried out by the Publications Office and the working group to develop the "eProcurement Ontology" (henceforth referred to as the ePO).

In the framework of this project, we will identify and give examples of each step of the process for creating the e-procurement ontology. Clearly specifying the roles of the different actors and the input required of them within the timeline of creating the ontology. The different phases needed to create the ontology and the intermediary processes within these phases will be clearly defined giving examples taken from the 3 use cases. In parallel to this process, a working group composed of stakeholders from multiple interested groups will be set up. This working group will decide by consensus on how the ontology should be developed at all stages and may decide to adopt the first draft of the specification proposed and described during the first meeting. This project will provide the working group with the process, methodology and technology to be followed for developing the final version of the e-procurement ontology.

Competency Questions

In order to prepare SPARQL queries and test the ontology the Working Group jointly with the OP development team, as experts in both the eProcurement domain and ontology development, shall work on the drafting of simple questions.

The methodology used to obtain the competency questions is as follows:


Use Cases: Transparency and Monitoring


User stories

User Stories are a method of helping identify information requirements. The method consists in drafting very simple sentence structured around three main questions:

  • Who is the beneficiary of an action (who benefits from it)?

  • What is the need?

  • What is the benefit?

The structure of the sentence is always like this: “As a <role of the user>, I need <something> in order to <benefit>.”


As a contracting authority (ROLE), I need to know the number of tenderers that have submitted a tender (WHAT DO I NEED?) in order to add it to the award notice (BENEFIT).


User Stories versus Competency Questions

Based on the user stories above, we will ask several questions that should be answered by the ePO taking into account Use Cases 1 and 4.

These are the so-called Competency Questions. Below we will provide some examples of User Stories versus Competency questions.