==="Prologue" and "00" Episodes===
When it comes to episodes that are numbered as "Prologue" or "00", unless there is a clear indication that an "episode 0" should NOT be considered as the first episode of the regular airing sequence, an episode 0 will be considered episode 1 on AniDB, as it is the first aired episode.
An example of something that should NOT be considered as the first episode of the regular airing sequence would be [http://anidb.net/a10569 Macross Delta]
For reference, the original discussion on AniDB's moderator IRC channel can be found [http://anidb.net/perl-bin/animedb.pl?show=creq&creq.show=1&creq.id=8033071#msg16237416 here].
'''When an "episode 0" is considered as episode 1 on AniDB:'''