In a social bookmark system like Delicious, tagging tends to be pretty free form, but it doesn’t have to be.
A new patent application from Yahoo! provides a slightly different look and feel for Del.icio.us. It covers many of the present day functionality of the site, but adds a different way of using tags that presently isn’t in use on the site.
The idea is to let people add some types of tags that can be easily used and understood by computer systems, and then possibly implemented into other types of applications.
For example, letting people tag pages with location information means that the system can then use that geographical information in maps, and mapping type applications. Including date and time information means that bookmarks can be integrated into calendars and timelines and other applications where time matters.
These “structured” tags add some possibilities by their association to formats (time, location, file type, etc) that hasn’t existed in Del.icio.us before. This kind of classification data also adds the possibility of presenting advertisements to the users of the social networking site.