SPLICE is a project to supply documentation and infrastructure to help with adopting shared standards, protocols, and tools for web-based learning tools. The project has designed a protocol for an embedded iframe to communicate with its host page.
These are examples that use the SPLICE protocol for communicating with a server, such as Runestone. They are all integrated into this PreTeXt book as an <interactive> that uses an @iframe attribute to embed an iframe from some other server.