@neckara

I tried to search a little in the Wiki, is this information in the wiki ?

I don't think so, honestly I've never used this function and I don't remember seeing anything about it on the wiki. But, that's why I like the forum, now it's registered here, if in the future someone needs this function, a simple forum search will solve it.

@KoCinsKy Are you logged in to your Retroachievement account? I saw that there is a bug with chd files and Retroachievement , I don't know if this is your case ...