DFO Common Data Dictionary

A mapping tool provided by the Canadian Marine Environmental Data Service (MEDS) to facilitate mappings between parameter markup dictionaries in the oceanographic domain.

The DFO Common Data Dictionary is a web-based tool for the management of multiple data markup vocabularies. The tool operates in two modes. The first mode gives the definition (owner, meaning, units, and a discovery term) in return for a parameter code or key. Records are returned for all keys (which are unique for a given owner) that include the input string using a case-insensitive match. However, matches are dependant on semantics being built into the key, which may not be totally reliable in some cases (e.g. BODC).

The second mode takes a text string from the user and returns all records where the string is included (case insensitive) in the code meaning field of the definition. Thus the markup codes from all entries relevant to the search string from all the dictionaries in the system may be obtained, forming the basis for a mapping.

The system currently (April 28 2005) includes vocabularies from:

  • Marine Environmental Data Service (MEDS)
  • Bedford Institute of Oceanography (BIO)
  • British Oceanographic Data Centre (BODC)
  • US National Oceanographic Data Center (NODC)
  • Maurice Lamontagne Institute (IML)
  • Canadian Institute of Oceanographic Sciences (IOS)
  • Northwest Atlantic Fisheries Centre (NAFC)

The system currently holds static versions of some of the component dictionaries. Mechanisms to automatically keep entries in line with the master databases will be implemented to make the system fully operational.

The developer of the system, Jean Gagnon at MEDS, added the following content:

Our Canadian participation with Data Dictionaries within the ICES/IOC SGXML and JCOMM/ETDMP groups has led to the creation of this web-based "Dictionary of Oceanographic Codes". The intent is to "expose" common codes (their meaning and associated units) as presently in use, thereby hopefully reducing the proliferation of new codes and striving towards standardization. This is a practical bottom-up approach and is open to anyone wishing to participate on-line. Each "owner" has full authority to edit/update, add new or existing codes under their ownership and adopt other owner's codes.

The approach we are taking at present is to convert to standard SI "symbols" nomenclature for all our "units" (particularly for the physical quantities), and then adopt the GCMD keywords to establish more accepted "categories" within these quantities and codes. We also plan to deal with mappings of unit conversions by defining "synonyms" with their proper references in the database.

Our first observation was the lack of standardization of associated "units", which appeared to be due to two fundamental problems. Firstly, because many of our oceanographic codes fell into "meta-data" categories rather than measurable "physical quantities" [as defined by the 1993 ISO Standards Handbook, Quantities and Units, 3rd edition, 1993 (ISBN 92-67-10185-4)]; and secondly, because of the lack of adherence to the.

We invite comments on the web site and its approach.

Jean Gagnon

Marine Environmental Data Services Branch

Direction du service des données sur le milieu marin Fisheries and Oceans

Pêches et Océans W12082 - 200 Kent Ottawa, ON K1A-0E6

Téléphone: (613) 990-0260

Fax: (613) 993-4658

URL:

mailto:GagnonJ@dfo-mpo.gc.ca

Reference URLs: 
DFO Common Data Dictionary
Posted January 12th, 2008 by rkl
in