According to the Wiki
https://wiki.jriver.com/index.php/Multiple_Artist_AlbumsComplete Album is defined by
all tracks are of [Media Type]=Audio
all tracks have exactly the same, non-empty [Album] value
all tracks are in the same folder - i.e. have the same value for the [Filename (path)] field
all tracks have sequential [Track #] values starting at 1
all tracks have the same, or sequentially increasing [Disc #] values (empty and 1 are considered the same)
In View Schemes, an Album is defined by tracks having a common Album Artist or Album Artist (Auto) value.
https://wiki.jriver.com/index.php/Album_Artist_and_Album_Artist_(Auto)
Although seemingly related, the Complete Album tag and the determinization of what an Album is are based on different criteria.