Standard Keys

Aside from match custom data and voting keys, there are several “standard” keys that can be added. Some standard well-known settings (like the time-to-connect, spectators, best-of) are always present in every game’s game mode: the developer can define, for each of those settings, if its value should be added to the set of the MCD keys and how to name the key that will contain it.
Time-to-connect Key

This key represents the time - in seconds - the game should wait for all the players to join the match. If a key is defined, FACEIT will send the configured amount of seconds inside that key’s value in the game_custom_data field of the match configuration request.
Spectators Key

This key represents the list of player identifiers who are allowed to join the match as spectators. If a key is defined, FACEIT will send the list of player identifiers inside that key’s value in the game_custom_data field of the match configuration request.
"Best Of" Key

This key will hold the “best of” value of whichever round configuration (of type “mixed” or “publisher”) is chosen for the match at competition creation time. If a key is defined, FACEIT will send the chosen round configuration’s “best of” inside that key’s value in the game_custom_data field of the match configuration request.
Flexible Factions Key

This key represents a flag which controls whether a match allows flexible factions or not. If a key is defined, FACEIT will send true or false inside that key’s value in the game_custom_data field of the match configuration request.