Data description and formats

Storage, retrievability, re-use and citability are made possible through a technical infrastructure, with which 4TU.Centre for Research Data closely follows the rapid developments.

File formats

The choice of file format is of essential importance in order to ensure that the research data will remain usable and ‘legible’ in the future. 4TU.ResearchData therefore strongly encourages the use of standard, exchangeable or open file formats. For the preferred formats, 4TU.ResearchData guarantees that the research data will remain accessible and that they will be migrated or converted if necessary.

4TU.ResearchData provides three levels of support for file formats:

  • Level 1: All reasonable measures will be taken to ensure that the file formats remain legible and usable. These measures include migration, normalisation and conversion.                   
  • Level 2: Limited measures will be taken to preserve the usability and legibility of the file formats.
  • Level 3: Access to the data object will be offered in the file format that was originally provided.

4TU.ResearchData has a complete overview of all file formats and types of support. It also has an overview of the preferred formats (Level 1).

Important: The table mentions only those formats that are currently archived in the 4TU.ResearchData archive. The table is regularly updated and revised.


OPeNDAP stands for Open-source Project for a Network Data Access Protocol. OPeNDAP makes it possible for datasets to be directly approachable through programming languages. OPeNDAP communicates with the data in a particular manner, thereby making local data available to remote locations. Data can be stored in the Network Common Data Format (NetCDF) in order to enhance user possibilities.

If NetCDF data are pasted together with OPeNDAP, it is easier to perform a ‘query’ that will return an accurately defined selection out of the data. It allows users to view a section of the data, thus saving a considerable amount of download time.

Our data experts will be happy to tell you more about the possibilities of OPeNDAP in making your dataset accessible. 

Additional information about OPeNDAP is available at and through our Data Browser.
Our own OPeNDAP server can be reached at  


Descriptive metadata are indispensable for the preservation, retrieval and re-use of datasets. They provide answers to questions concerning the person creating the data, the subject of the data, the type of file, geographic information and other aspects. In other words, metadata are ‘data about data’. 

Metadata make use of international standards for data exchange. This ensures that the information and the associated dataset can be found by search engines.

Substantive metadata are important primarily for the user of the data. For example, consider a codebook that tells how the data should be read or interpreted. In many cases, such information is added in the form of readme files or similar descriptions.

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