Google's decision to take its Mail and other key applications out of beta, raises a nagging question: when is a beta not a beta? When it's really an alpha, perhaps, or else a finished product. Confused? You will be: welcome to the wacky world of software development.

Fifteen or 20 years ago, you knew where you stood... roughly, at least. The process would begin with a codename -- something exotic, fashionable or war-like. It might be Chicago or Condor or Pink, for example, and it would become a placeholder for a set of ideas. An operating system that can run on multiple hardware architectures, or an object-based file system. It didn't matter whether or not you had written a single line of code; the PR machine had a moniker, the press had a sniff of a story and the very lack of substance and perpetual rumour, claim and counter-claim only served to keep the world interested.

The next station of the cross would be an alpha: a ragged, half-baked, mind-those-sharp-corners lump of code, specially designed for geeks and sure to crash your shiny new PC, leaving only a few slivers of beige case, a mangled hard drive, an ejected floppy and a charred turbo button.

The beta wouldn't be much better but went out to a wider community of people who skulk in labs, write reviews and so on. The ponytails would delight in these disks stamped with white labels and warnings. They were for an exclusive set and possessing such a disk was akin to owning a copy of The Basement Tapes in the Sixties.

The vast majority of us never touched an alpha or beta but if we knew somebody in the right club we might get a final, pre-release version of the code, deemed stable and only likely to get pulled from commercial release in the event of a 'showstopper' -- a bug so significant that walls would crumbling down were it allowed to survive and prosper.

The pre-release code journey was changed in large part by Microsoft in the early 1990s when it began to release significant numbers of beta releases to the development community. Such was the excitement about the next versions of Word, Excel or Windows that these started to find their way into the hands of your average PC enthusiast. Microsoft was so successful with the policy that it could even charge people to go on the beta programme. Nice work if you can get it and if you were Microsoft you could get it all the time.

The internet begat another phase, that of the eternal beta and very public, iterative development. Post a program online and even if it played home to a colony of bugs your Get out Of Jail Free card was always there in a little badge next to the site masthead. Eventually this got crazy. Until today, GMail had been in beta for five years -- that's about three and a half years longer than a Windows release spends in beta.

What does beta mean today? Not a lot. So maybe what we need is an agreed standard, a traffic light that tells you what's safe to use, what's work in progress and what's ready for action. In fact, given the mania for plugfests, SIGs, TLAs and manifestos of intent, there probably is such a scheme underway - it's just in beta.