EventNett keywords and categories
Each event and location can be given up to 20 keywords (often called tags) to help group them with similar events and locations. Keywords are limited to single words and must not contain any non-alphanumeric characters. When adding a list of keywords to an event or location, or when including them in the search panel, you must separate them with spaces.
In the event and location views, keywords are displayed as links that will add them to the current search and then re-query.
One way that EventNett keywords are different from tags in other web sites is that keywords can have synonyms. When a keyword is given a synonym, searches using that synonym will return items as if the keyword were used. So, if the keyword "theater" has the synonyms "cinema" and "theatre", searches using either "cinema" or "theatre" will return objects that have the "theater" keyword.
Synonyms can be added from within the Keywords tab in the admin view. There, you can also rename or merge keywords. Synonyms eliminate the issue of having similar tags that may be missed in a search (e.g. the user types "cinema" and misses events with "theater"), but they also introduce the risk of over-generating search results. If a keyword is given too many synonyms, even very specific keyword searches may return a large number of results. Because of this, synonyms should be added carefully.
Another way the EventNett keywords differ from tags is how they are used to create categories. The categories are not a fixed list but are instead the 10 most popular keywords in EventNett, so they can change over time. Categories were created to provide quick access to the most common types of events.
This method was chosen as a compromise between creating a rigid structure of classifications or having keywords alone classify objects. When categories alone are used, an item gets placed in one when it may be appropriate to place it in several. Sites will try to mitigate the problem by introducing a hierarchy of categories. Ultimately, for events it's better to categorize them as, for example, both Diningand Music instead of choosing one over the other.