1. Hierarchical: In this type of relation, terms (items in taxonomy) are connected hierarchically. For example Books can be categorized as Novel, Drama, Science Fiction etc. Then Novel can be subcategorized in different ways. So these represent hierarchical relationship in taxonomy.
2. Equivalent: Two terms can be equivalent. For example TV and Television are equivalent.
3. Associative: In this case terms are related anyway. For example Television and Radio are related in some context.
How taxonomy types/relations are used in SharePoint?Taxonomy is used mainly to tag content but how these three taxonomy types are used in SharePoint for tagging content. For your information only Hierarchical and Equivalent content types are supported in SharePoint. For example you are uploading a video in a site developed with SharePoint. You want to tag the video with metadata so that user can find the video easily using search functionality. While you will upload the video you can select from existing term from taxonomy or enter a new/existing term(s) for this video. Say you are uploading a BBC TV program on famine in Africa. Then you can select/enter terms: TV, BBC, Famine, Africa. Now consider how we can organize these terms with taxonomy supports in SharePoint. Take a look at the figure 1 where you can find three sections:
1. Hierarchical taxonomy section: User will select from a predefined set of terms from taxonomies.
2. Upload video section: Upload the content, i.e., video.
3. Keyword (equivalent taxonomy) section: User will enter and as he/she will enter, suggestions will come up. As you can see in the image below, while user is typing BBC suggestion is coming up with British Broadcasting Service (BBC). Here BBC and British Broadcasting Service are equivalent term in the taxonomy. So whether user enter BBC or British Broadcasting Service, a single term (may be BBC or British Broadcasting Service) will be selected. So if another user search video by BBC or British Broadcasting Service, this will be selected as BBC and British Broadcasting Service are the same.
Figure 1: How Hierarchical and Equivalent taxonomy can be used to tag content (i.e., video)
How to define Hierarchical and Equivalent terms in SharePoint 2010To define a term in SharePoint 2010, go to Center administration site and navigate to ‘Application Management’. Then navigate to ‘Manage Service Applications’ under Service Applications. Then select the metadata service and you will be navigated to ‘Term Store Management Too’. You can easily define hierarchical terms. However to define any Equivalent terms, define any equivalent term first. For our example of ‘Television’, define Television first. Then you will find an option for defining equivalent term for television where you can define TV.
Figure 2: Define Equivalent Term
As shown in the figure 2, you can define multiple equivalent terms for one term.