Affects: Documentation (Ref Guide, User Guide, etc.)
Help Desk Ticket Reference: https://c.na7.visual.force.com/apex/Case_View?id=500A0000006mBvOIAU&sfdc.override=1
project_key: SOA

We'd like a service secured by one set of credentials (i.e. a system user) to be able to invoke another service using credentials other than the invoking user's.  An example use case might be having an Action Pipeline that validates credit for the current user.  (The credit must be checked with an external site, using 'our' credentials rather than the user's.)