>>Not "must" as such - it will work - but you may run into mysterious problems which may be hard to debug. I still have one query which will run on any development machine, but will throw an error at the users with SP1 runtimes.
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>Doesn't it depend on where the bug lies?

Exactly. Trying to find it is tough, because you can't reproduce it (you're developing with SP2), and runtime incompatibility, which occurs in few rare cases, is very low on the list of suspects.

>If the problem was with the generated p-code then recompiling in newer revision of the compiler fix the problem. If the problem is in the p-engine then using newer revision runtime should correct the problem. I'm inclined to believe that the many of the problems were with the p-engine -- so running with the newer runtime should fix the problems w/o requiring a recompile.

Yep. Except it's not an option - the customer's IT staff can't be trusted to keep two geese drawn on paper, not to mention to distribute an update to _all_ the workstations. So this one bug had to be worked around, instead, by using code which doesn't use any SP2 features. That was the easy part; the tough part was determining the cause.