Drupal Enterprise 7: Add a New Vocabulary to an Existing Content Type
The following instructions are for websites using the default UMN Drupal Enterprise 7 configuration.
To use a new vocabulary to help organize your site, you first need to add it to a content type. The first time you add a vocabulary to a content type, you need to make a field for that vocabulary. Every time after the first, you will reuse the field you created for the vocabulary to add that vocabulary to additional content types.