Chris is the real expert on these things, but is off-line over the holidays. I think the problem is that some vendors don't understand all the nitty-gritty technical terms any better than you or I do, since 72-pin SIMMs are hardly leading-edge technology any more.
I bought a 64Mb SIMM for my Mystic from a friend in the UK, who commented about it, "It won't work in the 6200/6300 series or the LC III, or 550 series. It will work in a 475 but can compete for space with other things. I suspect it may work in a 630 but haven't been able to test it."
It does work well in my Mystic, which is the important thing!
It's a bit like SCSI - more a black art than a science.
