Thesaurus is a table (one column) which contains keywords for individual grouping and/or retrieval of data sets. Keywords can be freely defined by the curator.
When opening the edit window (Fig 2), it shows an empty list. By typing an expression in the input field and pressing <Search>, a search following the syntax contains is performed. A list of keywords is shown having the expression somewhere in the word.
A special version is the technical keyword starting with an @... These keywords are for queries using PANGAEA Search, that exactly match datasets that contain this keyword exactly using the @... syntax. Technical keywords can be also searched by entering the keyword without @... In this case also datasets where the keyword appears somewhere else are hits. Technical keywords cannot contain spaces, only characters matching regular expression
/@[0-9a-zA-Z]+/. Technical keywords can also be used for OAI-PMH harvesting to provide collections of data sets for Portal (e.g. the CARBOOCEAN portal harvests OAI set "CARBOOCEAN", which are all datasets that have the tech keyword @CARBOOCEAN). The set name and so the keyword is case-sensitive (according to the spec) in this case. The OAI set name is the keyword without @. Before adding keywords for OAI sets, think about, if the set can also specified using the project id. A list of current defined OAI sets can be found at: http://ws.pangaea.de/oai/?verb=ListSets
Internally, PANGAEA also defines more technical keywords automatically (they do not appear in 4D):
@projectXXX, @eventXXX, @authorXXX, @piXXX, @deviceXXX, @locationXXX, @topotypeXXX, @basisXXX, @campaignXXX, @geocodeXXX, @paramXXX, @methodXXX, @refXXX (reference), @datasetXXX
where XXX is the numeric ID of the corresponding table, not all of them can be currently used with OAI-PMH (only the not-so-fine grained ones, see OAI "ListSets" verb above).
Keywords are not case sensitive and are not visible in the final data set layout as presented on the Internet. Non-technical keywords can contain spaces. PANGAEA Search will find them in a similar way as any other information in metadata.
The XML schema tag for a keyword search is