C2MS13 — Explain why messages are called Contact Reservation

The Contact Reservation messages are not "Contact Schedule Messages" because in operational practice a contact schedule includes more data than simply time and antenna for an SV. Additionally, a "contact schedule" prorbably maintains some form of contact requirements, and may contain a command plan, set of automation tasks to perform, etc. So, we viewed reserving antenna time ans a PART of the schedule rather than the schedule itself.

It would be good to add a description about this to section 8.15.

And maybe look at each case where we use the phrase "scheduling messages". Like the title of 8.15, in particular. To me, it's OK that we say this because these are messages "related" to scheduling, but specific to reserving antenna time.