Right, the uppercase conventionally means 1024 so it should be kB or ko for 1000. There are some odd rules, like L for liter because of readability or some other reason. I've also learned in (French) school that we shouldn't use kL, that it doesn't exist. It does exist, but we apparently don't want to use it and use hL instead. Some people thing it's a linear unit and not a cubic unit. We count liters like we count potatoes and we use m3 for volume math.

Here it is either KB or KiB, depending on the meaning. IRC, KB is the only exception from the rule.

The SI standard is international and doesn't admit a K prefix, only k or Ki.

Kelvin Bytes?