 It also makes an effort to promote less common varieties of beer, including stout, porter, and mild, as well as traditional cider and perry.CAMRA's states that real ale can only be served without the use of additional carbonation.This means that "any beer brand which is produced in both cask and keg versions" is not admitted to CAMRA festivals if the brewery's marketing is deemed to imply an equivalence of quality or character between the two versions.