Convert string to uppercase when comparing after normalizing instead of lowercase
While doing string comparison after normalizing
(converting both string to upper case or lower case) we
should always use the upper case. Upper case is optimized
for normalization.
A small group of characters, when
they are converted to lowercase, cannot make a round trip.
To make a round trip means to convert the characters from
one locale to another locale that represents the same
character data differently, and then to accurately
retrieve the original characters from the converted
characters.
Converting to uppercase rather than lowercase can also
prevent incorrect behavior in certain cultures. For
example, in Turkish, two lowercase i's map to the same
uppercase I.
Vikram