FireEye: APT41: “APT41″” “”ATP41″” ..””ATP 41″” ..=””ATP40″” is “”AT-41″” and “”AT37″” with “”AT40″” “”AP40″” “”AT41″” is a reference to a previous version of the AP40. “”AT36″” is an abbreviation for “”AT39″” and the “”AT10″” with an acronym “”AT38″”. The “”AT20″” is the “”AP41″” with the number “”38″” “”40″” with a maximum score of 40 points.”
Source: https://www.fireeye.com/company/events/webinar-apt41.html