silverstripe-dms/code/model/DMSTag.php

<?php
/**
 * Hold a set of metadata category/value tags associated with a DMSDocument
 *
 * @package dms
 */
class DMSTag extends DataObject
{
    private static $db = array(
        'Category' => 'Varchar(1024)',
        'Value' => 'Varchar(1024)',
        'MultiValue' => 'Boolean(1)'
    );

    private static $belongs_many_many = array(
        'Documents' => 'DMSDocument'
    );
}