This excerpt taken from the CVS 8-K filed Aug 15, 2006.
. Limitation on Suits. No Holder of any Debt Securities of any series may institute any proceeding, judicial or otherwise, with respect to this Indenture or the Debt Securities of such series, or for the appointment of a receiver or trustee, or for any other remedy under this Indenture, unless:
A Holder of Debt Securities of any series may not use this Indenture to prejudice the rights of another Holder of such series or to obtain a preference or priority over such other Holder.