Depois de pesquisar por mim mesmo, finalmente encontrei esta página com uma boa explicação.
link
Each rule is in the .aff file for that language. The rules come in two
flavors: SFX for suffixes, and PFX for prefixes. Each line begins with
PFX/SFX and then the rule letter identifier (the ones that follow the
word in the dictionary file:
PFX [rule_letter_identifier] [combineable_flag]
[number_of_rule_lines_that_follow]
You can normally ignore the combinable flag, it is Y or N depending on
whether it can be combined with other rules. Then there are some
number of lines (indicated by the )
that list different possibilities for how this rule applies in
different situations. It looks like this:
PFX [rule_letter_identifier] [number_of_letters_to_delete]
[what_to_add] [when_to_add_it]
For example:
- SFX B Y 3
- SFX B 0 able [^aeiou]
- SFX B 0 able ee
- SFX B e able [^aeiou]e
If "B" is one of the letters following a word, then this is one of the
rules that can apply. There are three possibilities that can happen
(because there are three lines). Only one will apply:
able is added to the end when the end of the word is "not" (indicated
by "^") one of the letters in the set (indicated by "[ ]") of letters
a, e, i, o, and u. For example, question → questionable able is added
to the end when the end of the word is "ee". For example, agree →
agreeable. able is added to the end when the end of the word is not a
vowel ("[^aeiou]") followed by an "e". The letter "e" is stripped (the
column before able). For example, excite → excitable.
PFX rules are the same, but apply at the beginning of the word instead
for prefixes.