According to section 603 of the FCRA, only information on credit issued to a consumer is allowed. If you are an AU, you do not fall under these categories, you are not responsible for the debt and did not receive credit. An AU doesn't have credit on this account and it's only the signor that is responsible. So, in essence, if an account on which you are an AU shows up on your report, it would be someone else's credit (the signor on the account). Here's the exact text to which I refer:
FCRA Section � 603. Definitions; rules of construction [15 U.S.C. 1681a] (what credit lines can be reported).
(l) Firm offer of credit or insurance.
The term "firm offer of credit or insurance" means any offer of credit or insurance to a consumer that will be honored if the consumer is determined, based on information in a consumer report on the consumer, to meet the specific criteria used to select the consumer for the offer, except that the offer may be further conditioned on one or more of the following:
The consumer being determined, based on information in the consumer's application for the credit or insurance, to meet specific criteria bearing on credit worthiness or insurability, as applicable, that are established
(A) before selection of the consumer for the offer; and
(B) for the purpose of determining whether to extend credit or insurance pursuant to the offer.
(2) Verification
(A) that the consumer continues to meet the specific criteria used to select the consumer for the offer, by using information in a consumer report on the consumer, information in the consumer's application for the credit or insurance, or other information bearing on the credit worthiness or insurability of the consumer; or
(B) of the information in the consumer's application for the credit or insurance, to determine that the consumer meets the specific criteria bearing on credit worthiness or insurability.
(3) The consumer furnishing any collateral that is a requirement for the extension of the credit or insurance that was
(A) established before selection of the consumer for the offer of credit or insurance; and
(B) disclosed to the consumer in the offer of credit or insurance.