Bruce, from what I can tell, it is reasonable to assume that all B230 engines having the round toothed design have an extended 100Kmi t-belt change interval.

Technical notes on round toothed belts at the Gates site support that notion. As a tidbit from that site, round toothed belts are more formally known as curvilinear profile belts and were designed for HTD (high torque drive) applications. The conventional chisel toothed belts are more formally known as trapezoidal profile belts.

You only have to look at a few parts sites to realize that round toothed belts were first used in the 1993 940s.

According to the Volvo (North America) 1993-1995 940 maintenance guides, the 100Kmi t-belt change interval applies to:
o all B230FD -those are the 1994-1995 NA B230s; TTBMOK (to the best of my knowledge) those all came with EGR (and Pulsair, at least in 1995)
o all B230FT w/EGR -TTBOMK all 1994-1995 B230FTs came with EGR; it wouldn't surprise me if all the 1993 B230FTs also had EGR
o all B230F w/EGR -those will only be found in 1993; again, it wouldn't surprise me if all the 1993 B230Fs had EGR
[EDIT for people running out to their cars to prove me wrong, the EGR valve is buried way down below the intake manifold next to the block, but its presence is most easily determined by the vacuum solenoid (having an obvious electrical connector) mounted on a bracket forward off the left strut tower]

The only apparent commonality in the Volvo specification is the presence of an EGR valve. I don't think it's a big stretch to conclude that all "improved" B230 engines coming off the line with the round toothed belt starting in 1993 also had EGR, as emission regs were pretty tight everywhere by then. In any case, when in doubt, change it early.
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Dave -940's, prev 740/240/140/120 You'd think I'd have learned by now