HIGH-VALUES (the highest ASCII value the character can hold).
In contrast to Low-Value, High-Value is the
highest value in the computer's collating sequence. It
is valid only with alphanumeric fields. When compared to
any other field, High-Value is always greater. The
internal representation of High-Value in most computers
is that of all bits in a byte set to one.
High-Value is not equal to either the letter Z or the number 9 unless
those characters are the highest characters in the
computer's collating sequence.