I have the following requirement for the OOTB Calendar Month view (in the default Calendar web part) :
Combine the Saturday and Sunday into a single column and show all events for both days in that column
Provide a way to filter by year (say, a dropdown).
I did search on the forum and I found this link , but the answer in this post did not give details.
I got the starting point from this post. As per my analysis the Calendar monthly view is rendered by the CalendarViewmonthChrome Control template. I could not find any XSL that is being used to transform the data to month view.
After looking at the source code and the application page templates for Calendar I could conclude that the Day columns Monday, Tuesday, etc. are coming from ApplicationPages:AjaxCalendarView, but I could not get any MSDN documentaion for this control.