Using standardised sets of terms (otherwise known as "controlled vocabularies") in metadata and to label data solves the problem of ambiguities associated with data markup and also enables records to be interpreted by computers. This opens up data sets to a whole world of possibilities for computer aided manipulation, distribution and long term reuse.
An example of how computers may benefit from the use of controlled vocabularies is in the summing of values taken from different data sets. For instance, one data set may have a column labelled "Temperature of the water column" and another might have "water temperature" or even "temperature". To the human eye, the similarity is obvious but a computer would not be able to interpret these as the same thing unless all the possible options were hard coded into its software. If data are marked up with the same terms, this problem is resolved.
In the real world, it is not always possible or agreeable for data providers to use the same terms. In such cases, controlled vocabularies can be used as a medium to which data centres can map their equivalent terms.
The controlled vocabularies delivered by the NERC Vocabulary Server contain the following information for each term:
Key — a compact permanent identifier for the term, designed for computer storage rather than human readability<br />
Term — the text string representing the term in human-readable form<br />
Abbreviation — a concise text string representing the term in human-readable form where space is limited<br />
Definition — a full description of what is meant by the term
All of the vocabularies are fully versioned and a permanent record is kept of all changes made.
Version 2.0 of the Server (NVS2.0), developed as part of the Open Service Network for Marine Environmental Data (NETMAR) programme, represents a complete rewrite of the internal software with both increased functionality and performance. Although the version 1.1 (V1.1) code will remain operational for the foreseeable future, existing users are urged to convert to NVS2.0 as soon as possible and the development of new V1.1 applications is strongly discouraged. The V1.1 and V1.0 documentation has been maintained as historical documents.