It may be undertaken by an external body or an internal department that reports independently from the program manager.
Where assurance also covers the solution this would include the business processes, systems, infrastructure, service and hosting.
Solution may also cover the approach to design, delivery and implementation.
Program assurance tends to cover three separate styles of assurance: Continuous assurance throughout the life of the program; Point reviews or periodic reviews; focused reviews that concentrate on a particular aspect of a program.
For very large programs all three would be undertaken with continuous assurance reporting to the program board on a regular basis, and point or focused reviews being undertaken at strategic points.