Actually they are alternative spellings: Disk is a variant spelling of disc, and the preferred US spelling of disc in all senses. It is also the majority spelling in the computing industry - Collins Concise Dictionary, 2001.
Ask Oxford (http://www.askoxford.com/concise_oed/disc?view=uk) says that disk is the US spelling of disc, but that IT uses the US spelling. Presumably similar to the usage of program rather than programme. As disk rather than disc is used in computing we should use disk - despite the fact that some would say it's an Americanism. -- "Disc" in en_GB translation should be "Disk" https://launchpad.net/bugs/68955 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs