We use the group availability to communicate the monthly uptime of a service to our clients, with this information they can see if the SLA has been met.
now if the client has had planned maintenance on there system, there uptime can be below the 99,9%for that month.
What we suggest is that if we see there up time in the graph isn't 100%, that we can add a note like "client maintenance" or "Windows updates". And when we send out the monthly Uptime report we would like to add the notes in the report so if the uptime is lower then 99,9% that the client also has an report on why that is.