- simple what/content pairs, e.g. Homepage: http://osstag.sourceforge.net
- single words (tags), e.g. perl, xml
-> aspect oriented tagging combines what/content pairs with tagging, e.g. encoding/perl, xml
- time-durations/time-frames/time-points, e.g: before 2006, between 050101 and 050715 or at 15-FEB-2002 03:00pm
-> should we support such tags so that everybody defines timeframes in a coherent way?
-> should we support any other standardized information?