Unidirectional players vs. bidirectional groups
MPA accepts two concepts of player interaction. In the unidirectional players concept, the title reports that player A has played with one or more players. This should occur for every player who has affected player A. As a result, each of these players appears on player A’s recent players list. All players should individually report their own interactions. Servers are also allowed to report batches of recent players in this way. In the bidirectional groups concept, all players are known to have interacted with each other. For example, in a four-versus-four shooter game or an eight-player race, the game can detect in advance that all players should appear in each others’ players list. They can call an API that has a list of players. MPA ensures that every player has every other player added to their recent players list. Only servers are allowed to submit bidirectional groups.Encounter types
MPA supports recording the type of encounter that has occurred. Titles can specify anencounterType field. It has the allowed values of Default, Teammate,
and Opponent. If unspecified, the field defaults to Default. Specifying this field gives
players the opportunity to more easily differentiate between various types
of encounters.