Registration of the System boundaries is a reliability quality registration. Typically, the Systems are defined based on process schemes, like P&ID's, where the boundaries need to be 'drawn' on these schemes.
The registration should clarify which equipment is in which system, and if particular equipment is not included in a System. Over time, this may involve updates of where the boundary lies.
As the boundaries should be registered, by drawing them on the process schemes, this can be done by tools like AutoCAD - but also by standard tools as PowerPoint. The attached video shows how to use PowerPoint to register systems boundaries. The action starts with formatting the slide background with the picture of the diagram.
These registrations can be stored in IMS for future use and reference. The reason we like this approach is that your don't need special tools, neither skills.