This excerpt taken from the CCO 8-K filed Dec 11, 2009.
Limitation on Guarantees of Indebtedness by Restricted Subsidiaries
The Company will not permit any Restricted Subsidiary of the Company, other than a Guarantor or an Immaterial Subsidiary, to guarantee the payment of any Indebtedness in excess of $10.0 million of the Issuer or any Guarantor unless:
(1) such Restricted Subsidiary within 30 days executes and delivers a supplemental indenture to the 2017 B Indenture providing for a Guarantee by such Restricted Subsidiary, except that with respect to a guarantee of Indebtedness of the Issuer or any Guarantor, if such Indebtedness is by its express terms subordinated in right of payment to the 2017 B Notes or a related Guarantee, any such guarantee by such Restricted Subsidiary with respect to such Indebtedness shall be subordinated in right of payment to such Guarantee substantially to the same extent as such Indebtedness is subordinated to the 2017 B Notes or such Guarantors related Guarantee; and
(2) such Restricted Subsidiary shall within 30 days deliver to the Trustee an Opinion of Counsel reasonably satisfactory to the Trustee;
provided, that this covenant shall not be applicable to any guarantee of any Restricted Subsidiary that existed at the time such Person became a Restricted Subsidiary and was not incurred in connection with, or in contemplation of, such Person becoming a Restricted Subsidiary. The Company may elect, in its sole discretion, to cause any Subsidiary that is not otherwise required to be a Guarantor to become a Guarantor, in which case such Subsidiary shall not be required to comply with the 30 day periods described above.