Zend\Tag is a component suite which provides a facility to work with taggable
Items. As its base, it provides two classes to work with Tags, Zend\Tag\Item
and Zend\Tag\ItemList. Additionally, it comes with the interface
Zend\Tag\TaggableInterface, which allows you to use any of your models as a
taggable item in conjunction with Zend\Tag.

Zend\Tag\Item is a basic taggable item implementation which comes with the
essential functionality required to work with the Zend\Tag suite. A taggable
item always consists of a title and a relative weight (e.g. number of
occurrences). It also stores parameters which are used by the different
sub-components of Zend\Tag.

To group multiple items together, Zend\Tag\ItemList exists as an array iterator
and provides additional functionality to calculate absolute weight values based
on the given relative weights of each item in it.