Execute User Clause for the Add Program Command

You can assign a user to a program object so when other users execute the program, they get the accesses available to the user specified in the program definition. This access inheritance includes both business and system administrative access, as well as any business object access the context user didn't already have that the program user does. 

add program DocActionTrigger execute user bill;

Only one user is ever associated with a program. For nested programs, the user’s access from the first program is inherited only if the called program has no associated user of its own. If the called program does have a user, then that user’s accesses are made available instead. Once the called program returns to the calling program, the latter's user is restored as the person whose accesses are added to the current context. Thus, only one person's accesses are ever added to the current context (not including access granted on a business object).