NativeVotes has 3 votes types for map voting: NativeVotesType_ChgLevel (a yes/no vote with wording for changing a level now, uses the map name as it details), NativeVotesType_NextLevel (a yes/no votes with wording for setting the next level, uses the map name as it details), and NativeVotesType_NextLevelMult (a multiple choice vote with wording for setting the next level, details are ignored because it uses the NativeVotes_AddItems instead).
Actually... why are you trying to write a map vote anyway... isn't that what MapChoosers are for?