Let me try an example (which of course is only illustrative and not definitive, given the paltry knowledge I have).

Let's take a simple access to some company's web server.
At the client end you have:
- some version of Windows
- some version of some modem driver
- some version of some video adapter/driver
- some version of some HD adapter/driver
- some version of DUN software
- some version of browser software
- some version of a keyboard driver
- some version of a mouse driver
- some version of security that is operational
- some version of TCPIP
- (possibly some versions of JAVA VM, script engines, plug-ins, VBRUNDLL, ???)
All of these may well start out packaged together but eventually they take their separate ways.

In addition to also having all of the above the company end might have:
- some firewall/security software (on it own OS???)
- some version of IIS
- some version ASP
- some version of ADO
- some version of OBDC
That's about all I can come up with for this.

But I think it goes even deeper. For instance, just as a user of Office95, Office97 and Office2000 it is obvious to me that different parts were written by different 'groups', simply as evidenced by the different (and bothersome) interfaces that are presented at different times. While these separate parts all work together, variations of seemingly unrelated things can cause their malfunction. Recently, for instance, I made a change to something not even remotely related to IE yet suddenly my IE needed to dial out whenever I started it.

I hope this gives you the idea.

Jim


>I dunno, Jim. What's your definition of semi-independent parts?
>
>>Well I'll take a 99.9999% objective any day!
>>MS makes it even tougher on itself (no doubt customer demand has MUCH to do with this) in that they support a huge combination of versions/fix-levels of a HUGE number of individual and semi-independent "pieces" (components). I'm betting that MS will eventually reduce the number of semi-independent parts SIGNIFICANTLY in favour of delivering 99.9999% reliable software.