In this section you will find definitions of key concepts related to the CLARIN:EL Research Infrastructure as well as answers to frequently asked questions about the the participation in the CLARIN:EL network, the use of the Infrastructure or technical and legal issues.

The CLARIN project is a european initiative to collect, organise and, finally, distribute to the research community language resouces in all european languages, through a research infrastrucure which will also offer language tools.  

This initiative mainly targets the research community but it also aims at the public. Organisation-wise, it has the form of a pan-european network of research centers and offers  

  • access to resources, services and language processing tools
  • language resources documentation through metadata
  • coordination of the creation, storage, management and access to the language resources
  • training and dissemination on the use of language technology. 

​CLARIN:EL is the Greek part of the CLARIN infrastructure. You can find additional information here.

By the terms Language Resources (LRs) and Language Technologies (LTs) we refer to language data (written or spoken) and to the tools used for their processing. We distinguish the following categories:

  • primary data
    • digital/digitised resources, such as written texts (e.g. digitised books, web texts, newspapers, corpora etc.), recordings of spoken language (e.g. interviews, radio broadcasts etc.)
    • video recordings (e.g. TV shows, facial expressions collections, gestures etc.) 
    • images (e.g. digital/digitised photographs with their captions etc.)  
  • processed data
    • various types of annotations of texts, sound and multimedia data, automatically or manually created (e.g. morphosyntactically annotated texts, transcriptions of spoken data, video annotations etc.)  
  • reference resources
    • various types of structured language data (e.g. word lists, dictionaries, thesauri etc.) which can be used for improved organisation, processing and study of primary data
  • language technology tools/applications  
    • tools and integrated applications that perform various types of language processing (e.g. multilingual text alignment, morphological annotation, lemmatisation, parsing, knowledge extraction etc.) 
    • visuallisation tools (e.g. integrated environments for the presentation of texts, mutlimedia collections, processing results etc.)

The CLARIN:EL Central Aggregator (or Central Catalogue) is the central repository of the CLARIN:EL Infrastructure, which is responsible for

  • the harvesting of metadata from the local repositories,
  • the organisation and the presentation of the metadata descriptions in a uniform catalogue and
  • the provision of access to the language resources to the network members and to the public.

Language Technologies (LTs) are workflows of tools for multilevel analysis, processing, annotation, enrichment and transformation of  language data.

Language Processing Services are services allowing the use of Language Resources and Technologies as well as their applications over the web.

Resource Provider is any organisation or individual that makes availble to the CLARIN:EL Infrastructure Language Resources, Technologies and/or Language processing services.

With the term Language Data we refer to digital language content of any form and medium, structured or unstructured.

Language Processing Tools are computational tools in the form of software, aiming at the

  • analysis,
  • processing, and
  • annotation of language data.

Organisations wishing to join the CLARIN:EL network and contribute language resources, tools and language processing web services to the Infrastructure, need to apply to become members by filling in the online Membership Application (in Greek).

Individuals wishing to join the CLARIN:EL network and share through the CLARIN:EL Infrastructure digital content, language resources and/or language processing tools they have developed, need to register to the Infrastructure with their academic or personal account. More information can be found here.

Organisations - members of the network can setup their own repositories, if they so wish. There they will be able to store, document, manage and curate their resources.  

Academic and/or Research Organisations wishing to join the CLARIN:EL network and contribute language resources, tools and language processing web services to the Infrastructure, first need to apply to become members (Online Membership Application).

After the examination and approval of the Membership Applications by the CLARIN:EL General Assembly (GA), CLARIN:EL Research Infrastructure makes contact with the Organisation for more information concerning the creation of an Institutional Repostitory for the new Member Organisation.

In order to deposit their resources, users have to be registered users and members of one of the repositories of the infrastructure. 

The procedure for language resource description and uploading has the following steps (detailed guidellines can be found here):

  • Initially, the user-curator needs to describe the resource, that is, to add its metadata. This can be done in two ways: 
    • using the dedicated tool (metadata editor) provided by the infrastructure. Once all the obligatory fields are filled in, the descritpion can be saved and stored.  
    • by uploading existing descriptions. This is the case of descriptions created independently of the tool; these have to be in the form of xml files. The infrastructure checks the compatibility of the descriptions with the metadata schema used by the infrastructure and, if they are compatible, they are stored.
  • ​Following the storage of the metadata, the next stage is the storage of the data itself. At this stage, the user-curator uploads the data to the Infrastructure. The data have to be compressed (files  'zip', 'tar.gz', 'gz', 'tgz', 'tar', 'bzip2', or 'bz2'). 
  • At the last stage, the user-curator is informed by email that the process has been completed. 

In order to process one of your resources (that is, a resource that is not stored in the infrastructure) with one of the web services of the infrastructure (that is, a language processing tool used over the internet), you first have to select the web service you want and then to upload your resource for processing, following these steps:

  1. From the central inventory homepage select browse.
  2. Filter the catalog of available resources to locate the web service you want.
    • first by restricting the catalog to only tools/services by selecting Filter by > Resource Type = Tool Service
    • and then restrict the results to only web services by selecting Filter by > Processing service = yes
  3. Select the web service you want.
  4. In the new page that opens, you can see the description of the service. Select the tab Access and then Use button to start uploading your resource.
  5. In the new page, click on Use this workflow button. Then upload the data you want to process.
    • NOTE: the resource must be in a zip file not exceeding 2 MB with a filename in Latin characters, with no spaces in it!
  6. Select Next.
    • NOTE: the resource you upload as well as the processing outcome will be stored for two (2) days in your repository (Institutional or Hosted Resources Repository). After this period, the resources will be deleted.
  7. The infrastructure informs you about the progress of the processing, and, when it is completed, you receive an email with a link to the processed resource.

You can upload only metadata descriptions to CLARIN:EL, while the resource itself might be available from elsewhere (another URL, through the owner etc.). However, resources that are not in CLARIN:EL cannot be processed with the available CLARIN:EL language processing web services. So, if you would like to use these services on your resources, it is best to upload the data as well as the metadata to the CLARIN:EL infrastructure.

Computational Support Services for the CLARIN:EL infrastructure are 

  • assignment of Persistent Identifiers (PIDs),
  • user authentication and authorization services (Authentication and Authorization Infrastructure, AAI),
  • storage services, and 
  • provision of computational power for the execution of web services.

The Hosted Resources Repository (HRR) hosts resources offered by providers that do not maintain a repository and makes them available to the users of the infrastructure. It also hosts the metadata descriptions of these resources and makes them available for harvesting by the Central Inventory. Finally, it offers user mamagement services to its users.

Each Institutional Repository hosts the resources of the relevant institution/organisation and makes them available to the users of the infrastructure according to the appropriate licenses. It also hosts the metadata descriptions for these resources and makes them available for harvesting by the Central Inventory. Finally, it offers user management services to its users.

The Central Inventory hosts the central resource catalogue of the infrastructure, which contains information for all the resources of the infrastructure. The Central Inventory gathers this information by harvesting the metadata from the local repositories. Finally, together with the CLARIN:EL portal, it hosts the technical and legal support services of the CLARIN:EL Infrastructure.


The person who is legally eligible to license and actually licenses the resource. The licensor could be different from the creator, the distributor or the Intellectual Property Rights (IPR) holder. The licensor has the necessary rights or licences to license the work and is the party that actually licenses the resource that enters the clarin:el network. The licensor will have obtained the necessary rights or licences from the IPR holder and may have a distribution agreement with a distributor that disseminates the work under a set of conditions defined in the specific licence and collects revenue on the licensor's behalf. The attribution of the creator, separately from the attribution of the licensor, may be part of the licence under which the resource is distributed (as e.g. is the case with Creative Commons Licences).

Distribution Rights Holder

The person or organization that holds the distribution rights. The range and scope of distribution rights is defined in the distribution agreement. The distributor in most cases only has a limited licence to distribute the work and collect royalties on behalf of the licensor or the IPR holder and cannot give to any recipient of the work permissions that exceed the scope of the distribution agreement (e.g. to allow uses of the work that are not defined in the distribution agreement).

IPR Holder

The person or organization who holds the full Intellectual Property Rights (Copyright, trademark etc) that subsist in the resource. The IPR holder could be different from the creator that may have assigned the rights to the IPR holder (e.g. an author as a creator assigns her rights to the publisher who is the IPR holder) and the distributor that holds a specific licence (i.e. a permission) to distribute the work within the clarin:el network.

Open licenses are ​standard​, irrevocable public licenses, that allow rights holder​s to share their work. Open licenses cover all types of ​work, such as content, data and software. 

E​very license allows ​users to use the licensed work ​subject to the terms that apply. ​They may license the work subject to attribution of the source or non-commercial us​e or non-derivative works ​or to share alike which means to redistribute the work or any derivatives thereof under the identical terms.

The most common open licenses are


Useful information on the different types of Public Domain Data (for example Public Sector Infomation, PSI) as well as their restrictions of use can be found here.


PSI licences constitute a key instrument for the release of huge amounts of information by Public Sector Bodies (PSBs). Useful information on key types of licensing, making reference to PSI licences as well, can be found here.

Useful information can be found here.