Core Vocabularies Handbook

Sharing data easily is indispensable for effective and efficient public services. The European Union has set rules and guidelines that intend to foster achieving that, including the Data Act, the Data Governance Act, the European Interoperability Framework (EIF), and the Interoperable Europe Act, which underscore the importance of harmonised data practices across member states. These initiatives emphasise that true interoperability goes far beyond just connecting systems at a technical level. They stress that data must be shared with a common understanding such that the meaning of the data is preserved as it moves from one system or agency to another. The Data Act lays out clear rules for fair data access and reuse, while the Data Governance Act builds trust in data sharing by establishing secure and transparent practices. The EIF provides practical guidelines on how systems should work together, not only in terms of technology but also in understanding and using data uniformly. The Interoperable Europe Act is aimed at removing barriers to public sector data sharing. It envisions a “network of networks” for seamless cross-border cooperation, supported by mandatory assessments and an Interoperable Europe Portal. In the public sector, interoperability refers to the capacity of different governmental bodies to collaborate effectively, allowing for the smooth exchange of information and delivery of services across various regions, sectors, and organisational boundaries. This capability ensures that data is shared and interpreted consistently, promoting reliable data sharing and access across multiple sectors and administrative levels, thereby enhancing policymaking and implementation.
At its core, interoperability is about working together to achieve shared objectives, regardless of organisational or geographical distances between participants. To achieve this, one has to elucidate interoperability’s multiple interacting sub-components. This could be along the line of the high-level conceptual model of the EIF, which intersects with national interoperability frameworks and domain-specific interoperability frameworks such as the INSPIRE Directive. In EIF, each higher layer rests upon an interoperable lower layer of infrastructure; e.g., organisational interoperability requires semantic operability such that information can be exchanged seamlessly, which, in turn, requires IT infrastructure interoperability.
They also can be viewed as layers of local, provincial, national, and EU-wide levels of interoperability to accommodate a plethora of e-Goverment information exchange scenarios. Alternatively, an interoperability framework can be envisioned as foundations upon which government services are built, or as one of the constituent pillars that enable goals such as citizen convenience, increased productivity, and lower costs of government operations.
In sum, there are two key reasons to seek interoperability:

While data exchange is an evident requirement for interoperability, there is a fine but crucial distinction between data format interoperability and semantic interoperability. A standardised and shared data format to store data lets one exchange data, such as creating an SQL database dump in one tool and seamlessly reopening it in another, or lets one send and receive emails that arrive properly in each other’s inbox.
Interoperability at the semantic level concerns the meaning of that data. One may have a format and language to represent data, such as XML, but with a tag <bank> … </bank>, neither the software nor the humans can determine from just that what sort of bank is enclosed within the tags. Such meaning is defined in artefacts including vocabularies, thesauri, and ontologies. A “<fin:bank>” tag in a document is then an implemented version of its definition at the semantic layer, where it has a definition and a number of properties specified, like that the fin:bank is a type of organisation with a board of directors and a location for its headquarters. This enables not only correct sending and receiving of data, but also exchanging data reliably, accessing the right data when querying for information and obtaining relevant data in the query answer, and merging data.
One recommended way to achieve semantic interoperability is to use Core Vocabularies, which is where the terms are specified and disambiguated.

A Core Vocabulary (CV) is a basic, reusable, and extensible specification for adding semantics to data and information that captures the essential characteristics of an entity in a context-neutral manner. Its primary purpose is to provide standardised terms that can be reused across various domains, typically realised as a lightweight ontology (optionally accompanied by a permissive data shape) and documented in a concise specification.
Core Vocabularies provide simplified, reusable, and extensible models that are subject domain agnostic and capture the fundamental characteristics of entities usually handled by public administrations.

Imagine you are starting a business in another EU country. To complete the registration, you need to submit a criminal record certificate and a diploma certificate to multiple public organisations. In many countries, this process is still manual—people must physically visit different ministries, request documents, and submit them in person or via email. Each organisation may use different formats and terminology, making it difficult for institutions to interpret and process the information correctly, possibly making mistakes during data entry that subsequently have to be corrected. Without a common reference vocabulary, these organizations interpret the data differently, making seamless exchange impossible.
Now, imagine an alternative scenario, one where this entire process is fully automated. Instead of individuals having to visit multiple offices, the ministries and public administrations would communicate directly with each other, exchanging the necessary information in a structured and consistent manner. The citizen could simply grant approval to the administration office to fetch the data from their home country that already had recorded the relevant data. This would eliminate the need for duplicate document submissions and avoid possible data entry issues, thereby reducing the hassle and costs of mobility. This is also the aim of the Once-Only Technical System (OOTS). Defining the what is one step; the how to achieve it is another.
How can different systems and institutions "talk" to each other effectively at the level of software applications and databases? The challenge is not only technical but also semantic. It is not enough for systems to simply exchange data—they must also be able to interpret the meaning behind the data in a consistent way such that it will not result in errors or so-called ‘dirty’–incorrect or incomplete–data. This requires a common language and (multilingual) structured vocabulary at both the business process level and the IT systems level.
This is where standards to declare the semantics play a crucial role. By using core vocabularies, public administrations can ensure that data and information is structured in a way understood by both humans and machines. Standardised models allow different organisations to recognise and process information without discrepancies, therewith reducing errors and the need for manual intervention. As a result, governments can facilitate seamless data exchange, ensuring that information is accurately shared, interpreted, and processed across systems, leading to more efficient approvals and interactions for businesses, governmental organisations, and citizens.

This book is intended for two main audiences: 1) administrative professionals and legal experts, and 2) technical experts and IT professionals.
Public administrations involve both legal/administrative experts and technical professionals. While they may not always “speak the same language”, they must* work together* to ensure smooth digital transformation. Semantics provides the common foundation that allows them to bridge their disciplinary differences and find common ground, enabling effective collaboration and thereby contributing to improved public services.
Each intended audience will gain new insights relevant for their respective roles

The SEMIC Core Vocabularies Handbook is designed to practically guide public administrations in achieving semantic interoperability. It provides clear guidance on how to use controlled vocabularies to create semantic data specifications that align with EU initiatives, how to reuse them, and how to implement them. Additionally, it outlines key use cases demonstrating practical applications of these vocabularies.
The Handbook has two types of content:

The structure of the main part of the handbook is as follows. First, several principal use cases will be introduced, which feature the most common, challenging, and interesting scenarios. It is augmented with other scenarios to indicate further possible usage. This is followed by guidelines for implementation, which includes procedures for how to create new models and how to map existing ones. These guidelines are demonstrated in the tutorials and examples for the use cases. Finally, it contains a glossary of terms for easy reference.