Yii RBAC and the use of the 'data' column

The CDbAuthManager class in Yii saves auth items (roles, tasks and operations) to the database along with some serialized data in the ‘data’ column. This serialized data is used only when the php code in the ‘bizrule’ is evaluated. Can someone list situations where this serialized data might be useful?

Qiang any input from you?

I’ve modified the database structure and sub-classed CDbAuthManager to enable accessCheck() to be done with fewer DB calls. I’m wondering whether to retain the ‘data’ column since I can’t figure out any situation where it is useful.