High Quality Content by WIKIPEDIA articles! In the Debian jargon, unstable is the development distribution of Debian. It is codenamed sid (after the boy next door who broke toys in Toy Story). As unstable never becomes testing, this codename is permanent, contrary to the codenames of stable and testing, which have volatile codenames (for instance, stable is currently known as Squeeze, but was Lenny before Debian 6.0 was released).