To display a Provider’s View Month window
The +/- 4 w buttons move forward/backward 4 weeks.
The +/- 6 m buttons move forward/backward 27 weeks (27 weeks rather than 26, to avoid users accidentally booking two appointments within a 6 month period (Note insurance rules)).
This behaviour ensures that the current weekday (as selected in the week view area) is also selected when you move forward/backward,
So, for example, if you're currently looking at a Friday, pressing these buttons will move to a Friday.
The behaviour of the similarly named buttons on the view months window is the same.