String comparison: Locale-sensitivity is never documented.
There are a few spots involving string comparison. The basic ones are here:
if(<variable|string> STRLESS <variable|string>) True if the given string or variable’s value is lexicographically less than the string or variable on the right. if(<variable|string> STRGREATER <variable|string>) True if the given string or variable’s value is lexicographically greater than the string or variable on the right. if(<variable|string> STREQUAL <variable|string>) True if the given string or variable’s value is lexicographically equal to the string or variable on the right.
However, nothing regarding the locale is documented. This also affects other functions such as list sorting.