Saving Treasures of the World Heritage at the Digital Archive DANS

Hella Hollander

Cite this as: Hollander, H. 2017 Saving Treasures of the World Heritage at the Digital Archive DANS, Internet Archaeology 43.

1. Certification for Digital Data Archives

DANS (Data Archiving and Networked Services, The Hague, The Netherlands), the Dutch national digital research archive, is an institute of the Royal Netherlands Academy of Arts and Sciences (KNAW) and the Netherlands Organisation for Scientific Research (NWO). Collaboration between the Dutch Cultural Heritage Agency (RCE) and DANS makes it possible to ensure sustainable archiving and unlocking of digital documentation of cultural heritage in a central national repository.

There is a great need to store archaeological data in a sustainable manner. What happens if an organisation loses their data, for example because the lifespan of the discs on which the excavation archives are stored is shorter than expected, or software ageing causes a system failure? An excavation cannot be done twice; the work to scan possible remaining analogue material such as photographs is enormous and probably the associated documentation (metadata) would be missing. Without information describing the image, the scientific value of it would be lost. Reorganisations within the archaeological sector are common and sometimes the data are forgotten as the result of changes in personnel. Data is not well described and cannot be understood anymore. A solid backup strategy is needed to protect this unique type of data presenting the world heritage.

In the Netherlands, DANS acts as a trusted repository to curate the archaeological data. The data remain accessible and usable in the long term at the national e-depot for Dutch Archaeology located at DANS. A wealth of archaeological excavation and exploration data such as maps, field drawings, photographs, tables and publications, are digitally accessible via EASY, the online archiving service. The description and data relating to thousands of archaeological research collections can be downloaded. The data are stored according to protocols and standards that make them easy to recover and share.

What actually is a trusted repository? DANS has the remit to provide reliable long-term access and therefore operates according to the OAIS (Open Archival Information System) model for digital archives. DANS holds the Data Seal of Approval (DSA), the internationally recognised quality mark for trusted digital repositories. In 2016 DANS extended this basic DSA certification with the DIN 31644 certification, which is based on an externally reviewed self-audit. The highest standard is the ISO 16363 and DANS has recently completed the test application for this certification. As a Regular Member of the International Council for Science – World Data System (ICSU-WDS), DANS is certified according to international standards and seen as a trustworthy party in terms of authenticity, integrity, confidentiality and availability of data and services. The preservation policy of DANS outlines the principles of sustainable archiving. Constant monitoring and biannual revision of this preservation policy improves the quality of the archive as the impact of threats and risks are understood. National and international agreed standards for digital preservation are followed and audits take place on a regular basis.

2. Hidden Treasures in the Sea of Data

The electronic archiving system EASY was developed in-house by DANS as an open-source system that makes self-archiving possible. A user-friendly interface helps data creators to deposit their own data, together with the metadata that describes the research project plus metadata that describes the files. EASY uses the international Dublin Core standard. DANS will process the submitted dataset by checking the completeness and clarity and ensuring that the data are stored in accordance with the DANS list of preferred formats (see Table 1), which guarantees long-term usability and accessibility (Gilissen 2013).

Table 1: An overview of the DANS preferred and acceptable formats
§TypePreferred format(s)Acceptable format(s)
2.2 Text documentsPDF/A (.pdf)ODT (.odt) MS Word (.doc, .docx) RTF (.rtf) PDF (.pdf)
2.3Plain text Unicode (.txt) Non-Unicode (.txt)
2.4 Markup language XML (.xml) HTML (.html; .xhtml) Note: When valid and complete (see notes) If needed: Related files: .css; .xslt; .js, .es (see notes) SGML (.sgml)
2.5 Spreadsheets ODS (.ods) CSV (.csv) MS Excel (.xls, .xlsx) PDF/A (.pdf) OOXML (.docx, .docm)
2.6 Databases SQL (.sql) SIARD (.siard) DB tables (.csv) MS Access (.mdb, .accdb), (v. 2000 or later) dBase (.dbf) (v. 7 or later) HDF5 (.hdf5, .he5, .h5)
2.7 Statistical data SPSS Portable (.por) SPSS (.sav) STATA (.dta) DDI (.xml) data (.csv) + setup (.txt) SAS (.7bdat; .sd2; .tpt) R(*)
2.8 Raster images JPEG (.jpg, .jpeg) TIFF (.tif, .tiff) PNG (.png) JPEG 2000 (.jp2) DICOM (.dcm) (by mutual agreement)
2.9 Vector images SVG (.svg) Illustrator (.ai) EPS (.eps)
2.10 Audio WAVE; BWF (.wav) FLAC (.flac) AIFF (.aif, .aiff) MP3 (.mp3) AAC (.aac, .m4a)
2.11 Video MPEG-2 (.mpg, .mpeg, …) MPEG-4 H.264 (.mp4) Lossless AVI (.avi) QuickTime (.mov) MKV (.mkv)
2.12 Computer-Aided Design (CAD) AutoCAD DXF v. R12 (.dxf) AutoCAD, other versions (.dwg, .dxf)
2.13 Geographical Information (GIS) GML (.gml) MIF/MID (.mif/.mid) ESRI Shapefiles (.shp & related) MapInfo (.tab & related) KML (.kml)
2.14 Images (geo reference) GeoTIFF (.tif, .tiff) TIFF World File (.tfw & .tif)
2.15 Raster GIS ASCII GRID (.asc, .txt) ESRI GRID (.grd & related files)
2.16 3D WaveFront Object (.obj) X3D (.x3d) COLLADA (.dae) Autodesk FBX (.fbx)
2.17 RDF W3C standards
2.18 Computer Assisted Qualitative Data Analysis (CAQDAS) Formats used in application, processed according to each individual file's data type Application's export formats (ATLAS.TI copy bundle; NVIVO export project; …) QuDEX

A researcher can find the data at DANS because it is stored online, has descriptive metadata, a descriptive codebook and is preserved in the right format. To get access a user needs to register by creating an account in EASY. After searching or browsing data the files can be downloaded by looking up the requested data collection or by using the persistent identifier link. Logging in is essential to be able to view/access the files. Downloading data is only possible when the conditions of use are accepted. The majority of the data is in the public domain; 80 per cent is open access. The remaining 20 per cent is restricted to professional archaeologists or available once a request for access to the data (permission request) has been granted. After 10 years of archiving their data digitally, Dutch archaeologists are used to sharing their data and increasingly trust other people who want to use such data. DANS encourages researchers to let their deposited data enter the public domain using the Creative Commons Zero (CC0) licence 'CC0 Waiver-No Rights Reserved', a common international open-access standard. In this category all possible rights, such as copyright and database rights, on the data files have been waived. The files are accessible to all users of EASY. The descriptive information on the research project and the data collection (metadata) is always freely accessible to all users of the Internet. This provides each potential user with the opportunity to find the files and to assess whether they are valuable to the research (Hollander 2014).

Regardless of the access category, users should always cite the data used. Every data collection at DANS has a Digital Object Identifier (DOI) and each data collection gives an example of how to cite the data correctly. This unique hyperlink reference is a permanent link to the intended source, independent of web address changes.

In 2017, over 28,000 archaeological excavation archives and reports can be consulted, criticised, analysed, studied and admired as hidden treasures discovered in the sea of data. This amount is growing daily.

3. Revision of National Regulations for Conducting Archaeology

In July 2016 the new Dutch Cultural Heritage Law replaced the old system of excavation permits with a new system based on certification. Archaeologists deposit their completed research results at DANS to boost their work's visibility and accessibility. Agreements to this end have been laid down in the quality standard for Dutch archaeology called 'KNA'. Over the last two years the Dutch archaeological community worked together to update this standard, and included digital methodologies and the statement that the archaeological data should be archived at a trusted repository. It was agreed that the certified archaeological organisation responsible for the archaeological excavation, survey or desk research should provide the documentation (including the standard report) to the Provincial or Municipal Depot within two years after completion of the fieldwork, and that for preference the long-term preservation of the digital data should be deposited with an e-depot. The e-depot is specified as one that is certified according to the European Framework for Audit and Certification of Trusted Digital Repositories with, at a minimum, DSA. Currently DANS is the only e-depot capable of this.

A national xml-protocol is introduced and used to describe, exchange and deposit data. This makes it easier to exchange the metadata of the documentation between the archaeologists and the provincial depots, depots of the municipalities, the Cultural Heritage Agency (RCE), the Royal Library (KB) and the national e-depot at DANS. The archaeological organisation makes an export of their database and uses this exchange xml-protocol to deliver their descriptive data to the various receiving depots. The aim is that the finds are stored in the provincial depot and the pictures, text documents, tables and maps are sustainably archived at DANS. Finds without documentation have no value and therefore their registration has to be connected within the broader context of documentation. Currently DANS is working together with several depots to connect the digital documentation, such as drawings, pictures, tables and their description, with the find registration system of the provincial depots. The provincial depots are investigating if it is possible to make a pan-provincial point for this descriptive xml data. The use of a national identifier and persistent identifiers makes it possible to create a permanent connection between the data in different systems. The process to make the data available to the broader public is encouraged by the Ministry of Education, Culture and Science (OCW).

After submitting the data at DANS (deposit instructions for archaeological data ), a data manager will process the data according to an established protocol. The metadata (extended Dublin Core) and the readability of the files will be checked. If this has not yet been done, the data archivist will also convert the files into a durable digital file format. This preservation format is often a simple text file format that is also used for exchange purposes (csv, dxf, mif/mid). The files will be archived both in the original (native) format and in the preservation format. In the presentation of the research project, the files will only be displayed in the preservation format. This will enable as many researchers as possible to reuse these data while using their own software. The 'DANS Preferred Formats' document is intended as a guide for data depositors. For each data type, a brief overview is given of the preferred format chosen, the use of the data, and any conversion possibilities. It is a dynamic document, and a working group within DANS is responsible for monitoring file formats and updating the recommendations based on new developments. It is far from the only list of recommendations regarding file formats in the world. There are numerous other sources and wikis about formats and risks. DANS has evaluated several existing documents based on their experiences with the file formats encountered (;;;

4. European Infrastructures Stimulating Integration

Driven by data, DANS ensures the further improvement of sustained access to digital archaeological research data with its participation in international projects like ARIADNE and PARTHENOS, on which this section will elaborate further.

To integrate archaeological data at a European level the ARIADNE Infrastructure was set up in 2013. Now, in 2016, a portal exists that has search and browse functionality, thus allowing researchers or the broader public with an interest in archaeology to cross search through time and space. Thesauri are helping to link related terms in different languages. The data of partners from 16 countries have commonalities that allowed integration (Binding et al. forthcoming and Aloia et al. 2017).

The focus of DANS within ARIADNE was to expand and improve access to the online archiving system EASY on an international basis. To increase data visibility to the general public and to integrate data on a European level, DANS ensures that archaeological and dendrochronological data are included in portals like Europeana and ARIADNE. DANS and The Dutch Cultural Heritage Agency (RCE) have a common interest to participate as one partner in the European infrastructure project to facilitate access to the Digital Collaboratory for Cultural Dendrochronology (DCCD) and contributed by cooperating with the international consolidation and expansion of the DCCD. Tree-ring data, coming from dendrochronological research done at archaeological sites, shipwrecks, buildings, furniture, paintings, sculptures and musical instruments, are made available by the DCCD.

International best practices and guidelines have been developed, such as the Guide to Good Practice on Dendrochronology:

'This document serves as a good-practice guide for the collection and archiving of dendrochronological data in the context of archaeological and historical research. The guide is aimed at both those creating dendrochronological datasets, and those that commission dendrochronological analyses. This guide does not cover the methods involved in dendrochronological analyses, but focuses on how to describe and archive the data and metadata involved in these analyses. This guide is concerned with best practice for the curation of digital information but does not cover the equally important aspects of the curation of physical samples. However, physical samples are the primary source of information in dendrochronological analyses and should always be managed alongside the digital data wherever possible. This ensures that samples can be re-evaluated where necessary and also re-examined as new analytical techniques are developed.' (

Work was done on the controlled vocabularies of EASY, which are based on the national thesaurus (ABR) and recently updated to a SKOS version by the Dutch Cultural Heritage Agency (RCE).

Dutch researchers carrying out research abroad (Greece for example) found their way to DANS. Data on Mediterranean archaeology have been added to the DANS repository, including the digital maps, field drawings, photographs, databases and publications regarding the sites, as well as collections from Zakynthos, Boeotia, Halos and parts of the Allard Pierson Collection. This is giving a new dimension to the online archiving system EASY and helped expand and improve access to the data. Also DANS encouraged and supported researchers to make mappings to CIDOC-CRM (Archeo), which currently takes place.

Participation of DANS at projects like ARIADNE and PARTHENOS makes it able to share expertise on topics on data preservation and dissemination within an international network of partners. Revising documentation and policies to continue format monitoring is done with the Archaeology Data Service (ADS) and the Deutsches Archäologisches Institut (IANUS – Forschungsdatenzentrum Archäologie & Altertumswissenschaften). Sharing knowledge with partners in Sweden, Slovenia and Austria about implementing new ways of systematic archiving of data but also the organisational aspects of setting up a repository is mutually beneficial. DANS improved and expanded the online archiving system EASY. A map-based search functionality was added that allows researchers a visual way of finding data (Figure 1).

DANS is leading the PARTHENOS Work Package on common policies and implementation strategies. Developing common policies to ensure the quality of the metadata, data and the repositories where the data is stored is one of the main targets of PARTENOS.

The PARTHENOS project empowers digital research in the fields of History, Language Studies, Cultural Heritage, Archaeology, and related fields across the (Digital) Humanities. It provides a thematic cluster of European Research Infrastructures, integrating initiatives, e-infrastructures and other world-class infrastructures, and builds bridges between different, tightly interrelated, fields. The motto of PARTHENOS is Investing in culture is investing in the future!

DANS is interested in the opinion of customers who have downloaded datasets from EASY. They are asked to express their appreciation for the data, or to criticise the quality. This can be helpful for other users, because this way a general impression of the quality of the dataset can be offered.

PARTHENOS is making it possible to position the archaeological community in an interdisciplinary field of sciences and to connect archaeological data for example with linguistic data or historical data. A pan-European infrastructure allows integration of the work previously done by other European infrastructures, projects or initiatives.

Expected flagship results of the project are:

Figure 1
Figure 1: A map-based search functionality in EASY

5. Recommendations for European Archaeological Policies

Storing archaeological data following policies, protocols and strict procedures protects the treasures of the world heritage from getting lost for ever. Cultural heritage has meaning to researchers, the broader public, policymakers, students and teachers, and has to be protected by national and international regulations.

The European Archaeological Council is setting the agenda by giving new meaning to the European archaeological heritage by striving to attain the highest possible standards of heritage management (Schut et al. 2015). One topic on their agenda concerns exchanging information in the digital era. The parties undertake to develop the use of digital technology to enhance access to cultural heritage and the benefits which derive from it (Article 14, Faro Convention).

After 10 years of expertise in the field of long-term preservation of archaeological data, DANS makes the following statements and recommendations for shared European archaeological polices to ensure good quality of metadata, data and repositories:


Aloia, N., Binding, C., Cuy, S., Doerr, M., Fanini, B., Felicetti, A., Fihn, J., Gavrilis, D., Geser, G., Hollander, H., Meghini, C., Niccolucci, F., Nurra, F., Papatheodorou, C., Richards, J., Ronzino, P., Scopigno, R., Theodoridou, M., Tudhope, D., Vlachidis, A. and Wright, H. 2017 Enabling European Archaeological Research: The ARIADNE E-Infrastructure, Internet Archaeology 43.

Binding, C., Tudhope, D., Cuy, S., Doerr, M., Theodoridou, M., Fanni, B., Felicetti, A., Niccolucci, F., Fihn, J. and Meghini, C. forthcoming 'ARIADNE: a research infrastructure for archaeology', Journal on Computing and Cultural Heritage.

Gilissen, V. 2013 ' Past the Opening: building towards the present, on-going dissemination of Dutch archaeological data as part of the DANS archive' in Opening the Past 2013 – Archaeology of the Future, Pisa 13-14-15/06/2013, MapPapers 1-III.

Hollander, H. 2014 'The Netherlands: the e-Depot for Dutch archaeology – archiving and publication of archaeological data' in Proceedings of the International Conference on Cultural Heritage and New Technologies (CHNT 18), November 11-13, 2013 Vienna.

Schut, P.A.C., Scharff, D. and De Wit, L.C. (eds) 2015 Setting the Agenda: giving new meaning to the European Archaeological Heritage, EAC Occasional Paper 10, Archaeolingua: Budapest.


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