[vonmoltke]

> In any program that has to handle just tenthousands of items ocasionally, knowing the difference between arrays, liked lists and pointer lists, or between various forms of hash tables, various forms of trees and sorted lists makes a big difference.

This is why I asked for clarification. To me "knowing the difference between" is different from knowing how they "work". Maybe it is just semantics in my head.

Edit because I forgot to address the second part:

> Is the fact that it doesn't use hash tables a coincidence or is it because the people designing and writing the system know their data structures and realized that hash tables don't fit the problem?

I suppose it is technically the latter, but it was glaringly obvious that hash tables weren't appropriate anywhere because none of our algorithms required associative lookups. Every algorithm had to touch every point of data it stored on every iteration anyway, so it was pointless to do anything but loop over it. Even if there had been a case where hash tables would have made sense, I'm not sure implementing a fixed-size hash table in C would have been worth the effort.