makeindex assumes word
-l option turns it into
letter ordering. The only difference is whether a blank is treated
as an effective letter or not. In word ordering, a blank precedes
any letter in the alphabet, whereas in letter ordering, it doesn't
count at all. This is best illustrated by the following
|word order||letter order|
Numbers are sorted in numeric order. For instance,
|9 (nine), 123|
|123 10 (ten), see Derek, Bo|
Letters are first sorted with uppercase and lowercase considered identical; then, within identical words the uppercase letter precedes its lowercase counterpart.
Patterns lead by a special symbol precede numbers, which precede patterns lead by a letter. The symbol here refers to anything not in the union of digits and English alphabet. This includes those which follow 'z' in the ASCII chart. As a special case, anything started with a digit but mixed with non-digits is considered a symbol-leading pattern instead of a number.