The TOC says that "certain codeshares" may be permitted. Any idea which codeshares are permitted or where I can find that information?
CERTIFICATE TERMS AND CONDITIONS
UA REF: GG ETC
1) To redeem go to United.com or call United Airlines Reservations 800-864-8331 (800-UNITED-1) or visit a United Ticket Office. There is no fee to book and redeem at United.com. Please note, there will be a ticketing service fee if you redeem at United Reservations, or a United ticketing facility. Fees vary, starting at $15, and are subject to change without notice. Certificates may not be redeemed through a Travel Agency.
2) You may view certificate details at United.com by clicking on Deals and Offers, Promotional Programs and enter Promotion code and PIN in the offer code box.
3) The certificate may be redeemed for credit up to its face amount only towards the purchase of an electronic airline ticket(s), where eligible, from United. The Promotion Code and PIN must be presented at time of ticket purchase and expire one year from original date of issue.
4) The certificate will not be honored in connection with prepaid tickets, tour packages or the purchase of non-transportation documents or items such as excess baggage charges, pet charges, MileagePlus Rewards, fee-waived tickets etc.
5) If the face amount of this certificate exceeds the cost of the ticket for which it is surrendered, any residual amount will be applied to the same PIN for use toward another ticket until either the original issued amount is depleted or the expiration date has been reached. This certificate cannot be combined with other travel certificates with promotion code TCVA or other travel certificates that represent a form of payment.
6) This certificate is not transferable and may not be sold or bartered. However, the original recipient of this certificate may arrange travel for another person if done without selling or bartering this certificate. Any sale or barter transaction involving this certificate, or any offer to sell or enter into such a transaction, shall render this certificate full VOID and thereupon this certificate shall no longer be redeemable by any person, including the original recipient.
7) Positive identification may be required when using this certificate toward the purchase of a ticket. United is not liable for loss, theft or use of this certificate receipt by a person other than the original recipient.
8) Travel permitted on flights operated by United and United Express. Certain codeshare flights may be valid for redemption.
9) United's Contract of Carriage applies to all travel on United Airlines and United Express.