This tutorial explains how to configure Orbiter vessels (including Spacecraft3.dll vessels) as payloads for the XR-class vessels (XR5 Vanguard and XR2 Ravenstar) using the Payload Management System. It offers a conceptual description of how the system works, two step-by-step examples, and a quick reference guide for payload developers.
This is a first draft, so comments are welcome! I hope this helps the Orbiter community develop lots of new payloads for these great vessels!