Race
"race_spawn" - nothing special
"race_flag" - REQUIRED - a race checkpoint. Use the spawn sequence to set what order you have to hit them in. You can have more than one checkpoint with the same spawn sequence, in which case the driver can hit either one to get the checkpoint.
you need to have at least one placed on the map to avoid the "map and gametype incompatible" message; but note that you might actually need more than one or need to set them for specific teams in order for the gametype to actually work.

Source: Bungie.net

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