(A.) Policy and legislation

(A.1) Policy objectives

In the digital single market strategy, interoperability appears as an important enabler for boosting competitiveness. Cross-border interoperability is also considered key for modernising public administrations.At the European level, the Once Only Principle has for the first time been mandated by the implementation, as established by the Single Digital Gateway Regulation, of a technical system that allows the cross-border exchange of evidence relevant for the procedures under such regulation. The Once Only Principle entails that public administrations do not request from citizens and businesses to provide data that are already held by any public competent authority -even foreign authorities-, but take actions to share these data always in respect of data protection regulations and other applicable legal requirement, so citizens and businesses are requested to provide data of each type at most only once.

In addition to the multilingual challenge, semantic interoperability is compromised by the lack of commonly agreed and widely used data models, divergent interpretations of the same data and the absence of common reference data (e.g. code-lists, identifiers, taxonomies, references to organisations, geospatial references, license collections, etc.).

The European Commission, in the context of the ISA2 programme (Interoperability solutions for European Public Administrations, Businesses and Citizens), undertook a number of initiatives to achieve semantic interoperability in Europe.

The ISA2programme contributed in this area through several streams of work, focusing on the development, promotion and management of common data specifications, further described in the relevant subsections: DCAT-AP as a data standard to describe open data catalogues and datasets; ADMS-AP 2.0 as metadata description of reusable solutions, such as legal templates, data specifications and standards, technical protocols and open source software; European Legislation Identifier (ELI) to facilitate the exchange of legislation data in Europe; and Core Vocabularies as generic, simplified and reference data models of important master data types used across public administration information systems and applications, such as persons, businesses, locations, public organisations and public services. Work performed by the ISA2 programme is continued through the Digital Europe Programme Regulation (Regulation (EU) 2021/694). In the Digital Europe Programme, the need for sematic interoperability is highlighted for the creation of the common European data spaces, a concept introduced by the European Strategy for Data as well as an enabler toseamless and secure cross-border electronic communication.

A new interoperability policy and governance will also work on defining a platform of shareable resources for cross-border and cross-domain services. Govtech incubators will also develop and test new components and specifications.

In all of these work streams, care is taken to ensure compatibility between the public sector and what the private sector can achieve, noting existing standards and specifications. There are accordingly some main technology areas that need to be addressed further and where standards are important for supporting the implementation of EU policy objectives:

  • DCAT-AP — This is addressed in detail in the section on Public Sector Information (PSI), Open Data and Big Data including a number of proposed actions;
  • Exchange of metadata on re-usable interoperability assets among national and international repositories: The Asset Description Metadata Schema (ADMS) is a metadata description of interoperability solutions;
  • Core Vocabularies to facilitate the development of interoperable IT solutions by ensuring a minimum level of interoperability for public administration master data usually stored in base registries.
  • The CPSVP-AP aims at describing public services in the same way across different Service Catalogues, to enable federation and search across such catalogues.

The European interoperability framework is a commonly agreed approach to the delivery of European public services in an interoperable manner that defines basic interoperability guidelines in the form of common principles, models and recommendations. It is expected that many recommendations can help also the private sector for B2B, B2G and B2C services. For example, the European standard on electronic invoicing is based on the concept of semantic interoperability and supports B2B and B2G transactions.

(A.2) EC perspectiveand progress report

In the Digital Single Market strategy, interoperability and reduction of administrative burden appear as important enablers for boosting competitiveness. Cross-border interoperability and data exchange are also considered key for modernising public administrations. At the European level, the Once Only Principle has for the first time been included in the eGovernment Action Plan 2016-2020, where it is one of the underlying principles. Subsequently, Member States have committed themselves to the Once Only Principle, such as in the Tallinn Declaration on eGovernment and the Berlin Declaration on Digital Society and Value-Based Digital Government. Furthermore, the Once Only Principle has been included in article 14 of the Single Digital Gateway Regulation adopted on 2 October 2018. Moreover, the recent Digital Decade Communication, sets that by 2030, everyone should benefit from “a best–in-class digital environment providing for easy-to-use, efficient and personalised services and tools with high security and privacy standards”. The implementation of the Once Only Principle is key to reaching this goal.


DCAT-AP is a specification based on W3C’s Data Catalogue vocabulary (DCAT) for describing public sector datasets in Europe. For more information, see chapter3.1.3 Public sector information

Exchange of metadata on re-usable interoperability assets (eGovernment)

Public administrations, businesses, standardisation bodies and academia are already producing interoperability solutions that, if (re)used, can facilitate interoperability among public administrations’ services. However, these are not always easy to find. ADMS-AP 2.0 is a common way to describe interoperability solutions making it possible for everyone to search and discover them once shared through the forthcoming federation of repositories containing solutions for promoting interoperability.

With the intention to facilitate the visibility and re-usability of interoperability solutions across-borders and sectors, the Commission has made available a large set of interoperability solutions described using ADMS-AP 2.0, through a federation of asset repositories of Member States, standardisation bodies and other relevant stakeholders. Through this federation, accessible through the Joinup12 platform, semantic interoperability solutions may be searched and are made available through a single point of access.

Core Vocabularies to facilitate the development of interoperable IT solutions

The Commission’s ISA programme is reducing semantic interoperability conflicts in Europe.

Agreement on definitions for the fundamental concepts should come firstly. These concepts are simplified data models which capture the minimal, global characteristics/attributes of an entity in a generic, country- and domain-neutral manner. Using a different terminology, these specifications are data models for important master data types used by numerous information systems and applications. These specifications are called “Core Vocabularies” in the ISA2 Programme.

Working together with relevant stakeholders from public administration, industry and academia, the Commission has made available a series of core vocabularies with high reusability potential: the core business, the core location, the core public service, the core public organisation, the core criterion and core evidence, and the core public service vocabularies.

In 2015, the core public service vocabulary application profile (CPSV-AP) also became available. Activities on financial reporting are under consideration.

Legislation interoperability

The European Legislation Identifier (ELI) to make legislation available online in a standardised format including technical specifications on:

  • legislation URI - Uniform Resource Identifier
  • legislative resource metadata
  • information exchange format ontology

Akoma Ntoso for European Union (AKN4EU) is the future machine-readable structured format for the exchange of legal documents in the EU decision-making process.

(A.3) References

(B.) Requested actions

Action 1 Following the Covid-19 situation and the experience gained with the current level of digitalisation of government services, the European Commission and SDOs to cooperate on analysing the current level of digitalisation and identifying gaps and needs regarding standards to support and further accelerate digitalisation. This should also include best practices.

Action 2 European Commission together with SDOs to facilitate a broad exchange with stakeholders and public authorities on standardisation and interoperability for eGovernment services.

Action 3 SDOs to identify and inform about standards that are available or under way and that are of relevance in supporting the European Interoperability Framework.

Action 4 SDOs to consider with ISA2 and Digital Europe programme the development of a set of standards around the EIF based on the specifications produced by the ISA2 and the Digital Europe programmes.

(C.) Activities and additional information

(C.1) Related standardisation activities

The Registered Organization Vocabulary which is based onthe Business Core Vocabulary has been published as a W3C Note by the W3C Linked Government Data Working group. http://www.w3.org/TR/vocab-regorg/

The W3C Data Exchange Working Group is chartered to create DCAT Version 3. Latest Draft is always at https://www.w3.org/TR/vocab-dcat-3/DCAT has known gaps in coverage, for example around time series and versions. DCAT has been successful and is in wide use, but these gaps must be addressed if usage is to continue to grow across different communities and the variety of metadata schemas is to reduce.Maximizing interoperability between services such as data catalogs, e-Infrastructures and virtual research environments requires not just the use of standard vocabularies but ofapplication profiles, initially created by DIGIT. This will also affect some of the Core Vocabularies produced by the Commission.

The Working Group is also tasked to deliver Content Negotiation by Application Profile and guidance on publishing application profiles of vocabularies, but those are not mature yet. More information can be found on the page of the Data Exchange WG: https://www.w3.org/2017/dxwg/wiki/Main_Page


ITU-T Focus Group on Data Processing and Management (FG-DPM) was created in March 2017. FG-DPM concluded its work with the development of several deliverables covering a variety of topics including the following:

  • DPM Framework for Data-driven IoT and Smart Cities and Communities
  • Technical enablers for open data platform
  • Data interoperability
  • Data quality management for trusted data

The complete list of deliverables is available here: https://www.itu.int/en/ITU-T/focusgroups/dpm

ITU-T SG20 are currently developing draft Recommendations and draft Supplements based on the FG-DPM deliverables. ITU-T SG20 approved Recommendation ITU-T Y.4473 “SensorThings API - Sensing”, Recommendation ITU-T Y.4560 “Blockchain-based data exchange and sharing for supporting Internet of things and smart cities and communities”, Recommendation ITU-T Y.4561 “Blockchain-based Data Management for supporting Internet of things and smart cities and communities” and agreed Supplement ITU-T Y.Suppl.69 “Web based data model for IoT and smart city systems and services”, Supplement ITU-T Y.Suppl.62 “Overview of blockchain for supporting Internet of things and smart cities and communities in data processing and management aspects”.

More info: https://itu.int/go/tsg20


The OASIS Transformational Government TC Framework (TGF) advances an overall framework for using information technology to improve the delivery of public services.

The OASIS Legal Document XML (LegalDocML) TC advances worldwide best practices for the use of XML within parliaments, assemblies, or congresses, within courts and tribunals, and generally for legal documents including contracts. The work is based on the Akoma Ntoso UN project. OASIS Akomo Ntoso is the basis of the future machine-readable structured format for the exchange of legal documents in the EU decision-making process, Akoma Ntoso for European Union AKN4EU).

The OASIS Code List Representation TC is defining an XML format for interchange, documentation and management of code lists.

The Single Digital Gateway regulation includes a system for once-only electronic exchange of evidences for electronic cross-border procedures. The regulation references the European Commission’s eDelivery Building Block, which uses the OASIS/ISO standards ebXML Messaging and AS4, the eID Building Block, which uses OASIS/ITU SAML.


Relevant IEEE activities include:

Standards activities:

  • The IEEE P2141 series of standards on blockchain technology for enterprise information systems and anti-corruption applications for centralized organizations.
  • IEEE P3119 Standard for the Procurement of Artificial Intelligence and Automated Decision Systems is a new IEEE standards activity.
  • IEEE P2863 - Recommended Practice for Organizational Governance of Artificial Intelligence

Pre-standards activities:

  • IEEE SA Industry Connection Program on AI-Driven Innovation for Cities and People; this program is focused on providing cities a governance mechanism to support responsible artificial intelligence systems (AIS);

IEEE SA Industry Connection Program on Alliance for Best Practices and Standards in Smart Cities; this program aims to develop close collaboration between the technology industry and city leaders and stakeholders towards smart city solutions across cities and regions.

  • The Ethics Certification Program for Autonomous and Intelligent Systems (ECPAIS)

For more information, please visit https://ieeesa.io/rp-egovernment

(C.2) additional information

Exchange of metadata on re-usable interoperability assets (eGovernment):

Several Member States already use ADMS-AP 2.0 to export interoperability solutions from nationalcatalogues (e.g. Germany).

The Open Geospatial Consortium (www.opengeospatial.org) has also standardisation work available relevant to e-Government.

Core Vocabularies to facilitate the development of interoperable IT solutions:

The DG DIGIT and the DG CONNECT have developed other vocabularies and technical specifications to provide interoperability solutions under the ISA2 Programme and the CEF Telecom Programme. The use of these vocabularies and technical specifications is being promoted by the European Commission through funding programmes so public and private organizations are developing pilot projects and solutions that use them. In this context, some common standardisation action will be required to allow the use of these vocabularies and technical specifications in compliance with the public procurement legislation. Currently, Core Vocabularies are used in the Once Only Principle technical infrastructure.

12 https://joinup.ec.europa.eu/collection/semantic-interoperability-community-semic/solution/asset-description-metadata-schema-adms/release/20