This appears to be Rover Ron's proprietary name for the improved MAF he sells. It's not clear to me what the extra 'AM' bit means. A far as I can see, his webpages doesn't clarify this. I'm sure there are hundreds of proprietary terms for items that may be used on these cars, but I don't think they should be included. The MAFAM is popular enough to scrape in.
Edd, DIN and ISO are standards organisations. The DIN term is an industry wide size for car radios, so a single DIN fits in a standard rectangular hole in the dash (no idea of the dimensions but it's bound to be in mm with several decimal places!!) 2 DIN or Double DIN is a slot twice the height of a single DIN one.
The International Standards Organisation or ISO poke their oar in everywhere. In the case of car radios they set an industry wide standard for how the connections on the back of the radio are presented. Both in plug type and style and which pin on which plug is 12v/ground/LH speaker/etc..