File Extension PLATO File Format PLATO Web Learning Network PLATO stands for PLATO Web Learning Network. This was last updated in March 2012 By Margaret Rouse Browse File Extensions Alphabetically: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # Ask a Question. Find an Answer. Ask your peers a question about this file extension. Ask a Question Cisco launches "Umbrella" Secure Internet Gateway Can I call upon the username of someone logged into the pc, and use it in a web link? Need advice on a career in IT?