backward combatability

humour /bak'w*d k*m-bat'*-bil'*-tee/ (Play on "backwardcompatibility") A property of hardware or software revisions

in which previous protocols, formats, layouts, etc. are

irrevocably discarded in favour of "new and improved"

protocols, formats and layouts, leaving the previous ones not

merely deprecated but actively defeated. (Too often, the old

and new versions cannot definitively be distinguished, such

that lingering instances of the previous ones yield crashes or

other infelicitous effects, as opposed to a simple "version

mismatch" message.) A backward compatible change, on the

other hand, allows old versions to coexist without crashes or

error messages, but too many major changes incorporating

elaborate backward compatibility processing can lead to

extreme software bloat.

See also flag day.

[Jargon File]

(2003-06-23)