Intern:Keyword

Keywords can be assigned to data sets, events, parameters, staffs, institutions, and references. They generally allow for grouping records in these tables and thus can be used to produce specific selections of records. We distinguish several types of keywords:
 * Technical keywords
 * Implicite keywords
 * Free keywords

Technical keywords

 * 1) Technical keywords should be used to produce non-ambiguous selections of records. E.g. you must define a technical keyword @IMAGES for the project IMAGES, because the scope of the term images is ambiguous and therefore it is likely that you will not get an exclusive selection of records for that project.
 * 2) Characters to be used are: {A-Z,a-z,0-9} (not allowed are {-,_, ,} all special characters and umlauts etc.)
 * 3) The first character is @.
 * 4) The first character after the @ character must not be a cipher.
 * 5) Do not define keywords having only meaningless or general terms that could be used also for another context.
 * 6) Put the general terms in front, followed by more specialized terms.
 * 7) Inner capitels (Binnenkapitele) could be used for better readability of composites.
 * 8) All queries including those for technical keywords are not case sensitive. So, using capital letter, inner capitels etc. is only for our internal work with these keywords. But technical keywords are case sensitive once defined => do not define a technical keyword again with another spelling! This is important for Sets on OAI and the Portals.
 * 9) The @Ref... keywords are reserved for usage by the PANGAEA system. It is an implicite mechanism that links references and data sets through these keywords.

Examples: @JGOFS, @JGOFSAustralia, @SummerSchoolBremen2003, @Zhao2004

Implicite keywords
There are technical keywords which exist by definition and which can also be used to produce non-ambiguous selections of records. They are neither visible in the 4D editorial environment nor are they embedded in the metadata (examples with XXX=ID of related table):
 * @eventXXX
 * @projectXXX (all data sets of project IMAGES (ID=12) => @project12)
 * @authorXXX
 * @piXXX (all data sets of PI Hannes Grobe (ID=9) => @pi9)
 * @datasetXXX
 * @paramXXX
 * @refXXX (all data sets of the reference with the ID=12345 => @ref12345)

Free keywords
They have no syntax constraints but should currently not be used (a structured approach for a thesaurus is under construction)

Editing keywords in 4D

 * from the menu choose "View" -> "Thesaurus" - by default the list is empty
 * type in the search box the keyword that you are looking for (or any part of the string)
 * double click the keyword to get into the editing mode, edit the line, and click save
 * in case you want to define a new record, click the "new" button, type in the keyword in the empty line and click save
 * now you can go to the table of your choice, select records from the list, and assign the new keyword by clicking on the "key" button