The Tags folder contain 4 scripts

- Default - Contain the class used for manage all the tags.
- Tags    - Manage Tags table.
- Users   - Manage TagUsers table.
- Modules - Manage TagModules table.

The Default class will process all the words and call the different classes,
for save each data in the correct place.

Before the tags are saved for one module-item,
all the ocurrences for these module-item and the current user, are deleted.
This is for delete the old tags that are not anymore for these item.
You canīt delete the tag, since can be used by other users.
You canīt delete the relation user-tag since can be used by other items.
So you only delete the relations for the item and the current user.

Each class (Tags, Users, Modules) are extencion of the Zend_Table,
and manage their own table.

The Default will call all of these classes for save and get the tags.

The functions are:

- saveTags($module, $itemId, $data)
Will parse the $data string, separate all the words by spaces,
and delete the stange characters (only is permited [0-9a-z]+).
The words are stored in lowercase and must contain more than 2 characters.

- getTags($limit = 0)
Get an array with all the tags for the current user
sorted by the number of ocurrences.
The $limit parameter is for get only this number of tags.

- getModulesByTag($tag, $limit = 0)
Get an array with all the modules
that are tagged with $tag by the current user.
The array contain per each module, the name of the module and the item Id.
The $limit parameter is for get only this number of modules.

- getTagsByModule($module, $itemId, $limit = 0)
Get an array with all the tags
that have the $module-$itemId for the current user.
The $limit parameter is for get only this number of tags.

- getFieldDefinition()
Return the field definitions for the return values of the tags.

- getModuleFieldDefinition()
Return the field definitions for the return values of the module-tags.
This function used the getFieldDefinition() defined on the Module class.
So each class return their array and their definition of them.