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_Taggable, 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.

// Create the item list
$list = new Zend_Tag_ItemList();

// Assign tags to it
$list[] = new Zend_Tag_Item(array('title' => 'Code', 'weight' => 50));
$list[] = new Zend_Tag_Item(array('title' => 'Zend Framework', 'weight' => 1));
$list[] = new Zend_Tag_Item(array('title' => 'PHP', 'weight' => 5));

// Spread absolute values on the items
$list->spreadWeightValues(array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10));

// Output the items with their absolute values
foreach ($list as $item) {
    printf("%s: %d\n", $item->getTitle(), $item->getParam('weightValue'));
}