Fortunately for me, a DBA in the county I live in only costs $20, so I went that route because their explanation was kinda vague to me too. After I had faxed it to them, they were like "and where's your business card?" So, I made a business card in Word, and they were all happy with that. Apparently, the legal document didn't cut it.
I think its just another way for a company (lots do this) to cover its derriere when using ICs but subscribing to some employee type dynamics.