The frame parts depicted in these drawings are as originally manufactured by APEX Enterprises.
The British Standard has lapsed and some manufacturers have modified their own production and have departed from the original definitions. (I do not know for what purpose.) The parts detailed here should fit with most other manufacturer's frame parts on a 'mix and match' basis. In those few cases that a good fit cannot be achieved with the aid of a craft knife you will have to blame those that will not adhere to the "standards" that took the appliance trade many years to refine.
There is a variant to the original system (the most recent version of which was developed by Richard Alabone). It is called the "Unified Frame". This is a large frame that will occupy a box formed by placing an empty shallow super on top of an empty brood box.