There are in general three types of window fastener for opening out hinged windows. A mortice plate fastener, wedge plate fastener and espagnolette fastener.
Traditionally Hinged Window Fasteners
Mortice plate and wedge plate fasteners are used on traditionally hinged windows in combination with a stay to hold the window open. They are available in traditional shapes and modern shapes, locking and non-locking, in most cases.
For inward opening hinged windows a fastener with a hook plate is required, many mortice plate fasteners come supplied with a hook plate as standard, if not they are generally available as a hook plate option.
Modern Window Locks & Fasteners
For modern windows hung on friction stays and using espagnolette locks an espagnolette window fastener is required. These can be distinguished from other fasteners as they have a square spindle to operate the window mechanism. They are available locking, non-locking and in an emergency escape version.