By stand-alone, we mean it can be formatted independent of the main source. Ordering By default makeindex assumes word ordering. The -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.
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. However, the same key with and without the actual part are regarded as distinct entries. This allows the encap operator to be used to set pages in different fonts, thereby conveying more information about whatever being indexed. For instance, given the same key the page where its definition appears can be in one font while where its primary example is given can be in another, with other ordinary appearances in a third. If this is to be formatted by languages other than , they would be defined differently.