-/* FIXME: This could be even more efficient if we caught SYSMIS when
- it first reared its ugly head, then threw it into an entirely new
- switch that handled SYSMIS aggressively like all the code does now.
- But I've spent a couple of weeks on the expression code, and that's
- enough to make anyone sick. For that matter, it could be more
- efficient if I hand-coded it in assembly for a dozen processors,
- but I'm not going to do that either. */
-