Do you sync with Google for your ISN calendar? If you do, you can create an appointment on your Google calendar that would then sync back to ISN, thus blocking your schedule on your ISN calendar. Please note, make sure to look at the Add Calendar Event feature within your ISN to see the 'allowed' time frame of events. For example, when the event will be occurring: Daily, Weekly, etc. If your Google calendar allows you to enter an event that re-occurs every fourth day, but that option is not in the ISN Add Calendar Event, that event from Google will NOT come over/sync to your ISN calendar!
In a future version of our ISN mobile app we have planned "appointment and inspection (order) creation" feature. It is an active project we are currently developing, however we don't have an estimated completion time of this project. You can find more information by clicking this link.
You will just need to provide/enter your Google username and password into ISN and the sync will happen in the background!