What is it? Just to translate into Dutch ...
It is PRE and POST orthographic language agreement.
AO=Acordo Ortográfico (Orthographic Agreement)
Portugal "reformed" the language in an attempt for all Portuguese speaking countries to write in the same manner.
For example: Brazil.
But it has created lots of conflicts among the people.
Basically, the agreement tried to simplify the words. For example: "correcto": in the new agreement they removed the "c" ("correto").
It is the spelling reform in use. Similar to this:
While the specific rules may not interest you particularly, I recomend porting some related rules (you will find it easy to port simple replace rules even if they are in Java), since they will be useful to Dutch as well.
1. A simple replace rule for all words that changed (Java).
2. XML rules for hiphenated compound changes
3. wordCoherency for words with multiple valid spellings (Java).
4. I added in pt-PT some special rules to distinguish words that have different meaning in the Brazilian variant. You can use an equivalent ruleset for Flemish words that appear in purely Dutch texts.
If you have trouble with any of the rules, just say so. I may be able to assist.
I understand about these reforms; we had a lot of discussion as well. But how to translate is still difficult.
What about "old" and "reformed"? Just keep it simple.
For translations, it may work well and I have no problem with it.
But note that those words are interpretative. While "reformed" is accurate and impartial, "old" would be inaccurate and emotionally charged.
Since this topic in Portugal is divisive enough, I would not recommend it for the source Portuguese text.
I translated it into before and after reforming, in Dutch. But that is not absolute as well, there have been multiple reforms for Dutch.