Mason's mitre
The terms "back mitre" and "mason's mitre" (or "miter") are often used interchangeably, but are actually different joints, used for different purposes.
Both joints are traditionally used in stone or woodwork. Neither joint requires that one part be "coped" (or fit) over the other.
In the back mitre, the actual joints follow the mitre and stile/rail joining lines, as shown in the following linked photo:
http://1.bp.blogspot.com/-fUa2ssQlMQM/UWH58DNXZ8I/AAAAAAAAAIw/6HiZ3ZYSwdg/s1600/4.3.2013+007.JPG
In the mason's mitre, the intersecting mouldings are carved within a single stone block or the woodwork's stile, with the rail or adjacent block having a straight profile. Please see the linked photo of a mason's mitre:
