ABCD Schema - Task Group on
Access to Biological Collection Data

A joint CODATA and TDWG initiative supported by GBIF

ABCD Schema 2.06 - ratified TDWG Standard

The Access to Biological Collections Data (ABCD) Schema is an evolving comprehensive standard for the access to and exchange of data about specimens and observations (a.k.a. primary biodiversity data). ABCD version 2.06 has been recommended by the TDWG meeting in St. Petersburg as the actual standard and has since then been ratified by TDWG members. This version is also used in a second ABCD reference implementation we are currently initiating. Please contact Markus Döring (M.Doering [at] if you are interested to collaborate in this effort.

Download or view ABCD 2.06: [.zip with .xsd's and doc's]  [in a single file .xsd]  [HTML documentation] [MS-Word]

A detailed description of ABCD 2.06 including its history and scope is given on the ABCD Wiki.

The ABCD Schema attempts to be comprehensive and highly structured, supporting data from a wide variety of databases. It is compatible with several existing data standards. Parallel structures exist so that either (or both) atomised data and free-text can be accommodated. Versions 1.2 and 2.06 are currently in use with the GBIF (Global Biodiversity Information Facility) and BioCASE (Biological Collection Access Service for Europe) networks.
Apart from the GBIF and BioCASE networks, the potential for the application of ABCD extends to internal networks, or in-house legacy data access (e.g. datasets from external sources that shall not be converted and integrated into an institutionís own data, but be kept separately, though easily accessible). By defining relations between terms, ABCD is a step towards an ontology for biological collections. 

Review process: Over the past years, numerous suggestions and questions were received. Together with the practical experience from the reference implementation of v. 1.2 this has led to a number of additions and changes in the schema. However, its basic structure has been largely preserved. Version 1.49 was submitted to TDWG for consideration as a draft standard during the 2004 meeting in Christchurch, and suggestions gathered there further contributed to schema development. ABCD 2.05 was submitted to the TDWG Executive Committee in time to be considered for voting in St. Petersburg. Following that meeting's recommendation, version 2.06, which incorporates final comments and ratified by the TDWG membership in November 2005.

ABCD will continue to evolve. Please email questions and requests to the editor (w.berendsohn [at] Please allow for some time for processing.

Supporting documents: CommentsCommented [pdf] - A collection of the comments made since version 1.0 was released and statements as to their incorporation in the schema. Much of this will end up in the documentation on the ABCD wiki. Changes from v. 1.20 [pdf] are documented separately and will be used in the semantic objects library for biological collections, where we want to unite the documentation for schemas and standards and their versions.

Mapping to other standards :
Mapping of Darwin Core and its extensions (incl. OBIS) to ABCD 2.06
Draft mapping of OECD-MDS (culture collections standard) to ABCD [valid for v. 1.30]
Draft mapping of EURISCO descriptors (plant genetic resources) to ABCD 2.06
Mapping of HISPID 3 to ABCD 1.49d
Mapping of ITF-2 to ABCD 2.00 (forthcoming)

Related efforts

The Darwin Core 2 (DwC) is a smaller set of data element definitions designed to support the sharing and integration of primary biodiversity data. DwC has also been presented to TDWG as a Draft Standard. See for details.
Darwin Core (DwC) and ABCD are complementary standards. Whereas DwC has a flat structure of 44 elements, ABCD has a hierarchical structure that supports repeating elements and complex types. In order to accommodate detailed data, often according to multiple standards, as well as free text alternatives where detailed data cannot be provided, ABCD contains about 700 elements. While making the mapping process and the development of data portals more demanding than with DwC, this complexity widens the application of the schema from a minimum-common-denominator approach for resource discovery to a standard that can that can meet the demands where more detailed data are needed.
To accomplish interoperability, the development of both ABCD and DwC will strive to keep both standards compatible on the element level, so that a mutual translation of documents will be possible. The elements of DwC have been mapped to ABCD to illustrate the strong overlap and the few existing semantic differences.

SDD and UBIF: We strongly advocate the development of a common schema for metadata (Unified Biosciences Information Framework UBIF) with other TDWG subgroups, in particular with the subgroup for Structure of Descriptive Data (SDD). Please join the discussion on the SDD TWiKi site.



This is a community-driven effort in which many people participate. Several projects and institutions have contributed to speed up and focus the efforts by supporting meetings and attendance to meetings, by supporting software development, or by providing the means for the preparation of draft documents for discussion. Many data models and standards have contributed to develop our knowledge about the problem domain. ABCD's Subgroup on Content Development has tried to incorporate these results in the development of the schema. In 2001, the ENHSIN project supported the drafting of a first DTD. In 2002, the development of the unit-level schema was the subject of the BioCASE project's workpackage 3 (schema development). The Singapore meeting of the Editorial group was sponsored by the Global Biodiversity Information Facility. The TDWG Subgroup on Structure of Descriptive Data (SDD) have contributed a great number of concepts to the current schema. CODATA has supported the task group (formerly working group) since 2001. See the Acknowledgements on the ABCD Wiki for individual contributors. Special thanks to Helmut Knüpffer (Gatersleben) for pointing out numerous orthographical errors and inconsistencies in annotation texts and to Gregor Hagedorn (Berlin) for his in-depth analysis of many of the topics related to this schema. The reference implementation of ABCD 1.2 was carried out by tasks under the European Commission funded projects ENBI, BioCASE, and SYNTHESYS (Networking activity D), as well as by two projects funded within the GBIF-Germany programme of the German Federal Ministry for Research and Education (GBIF-D Botany and SPECIFY). The collaboration of several European GBIF Nodes is also acknowledged. These projects have mapped more than 180 databases to the schema, providing extremely valuable input for schema development.

Working Group Homepage | TDWG Accessions Subgroup Homepage | CODATA | TDWG 

Page hosted by the Department of Biodiversity Informatics and Laboratories of the Botanic Garden and Botanical Museum Berlin-Dahlem. DISCLAIMER  
Page editor: Walter Berendsohn (w.berendsohn [at]

This page last edited on 07.04.2007