Does anyone know the precise details of this ruling?

I can't find the actual text of the guideline. It seems very ambiguous; "trained by a club's own academy" doesn't say for how long! Ie are feeder clubs covered, and would the likes of Flamini be considered "home grown" just because he has spent some time in Arsenal's academy?

Academy plan
Under the proposals, the 'A' list that teams submit for UEFA club competitions would continue to be limited to 25 players, and from season 2006/07, at least two places on this list would be reserved for players trained by a club's own academy with a further two places for players trained by other clubs from within the same association of the said club.

Extra places
In the following two seasons, one additional place for a club-trained player and one additional place for an association-trained player would be reserved on the 'A' list, so that by the 2008/09 campaign, each club would have in its 25-man squad four club trained and four association-trained players.