Here is a list of all documented enum values with links to the class documentation for each member:

• kDeferrable : storages::postgres::TransactionOptions
• kMajority : storages::mongo::options::WriteConcern
• kNearest : storages::mongo::options::ReadPreference
• kPrimary : storages::mongo::options::ReadPreference
• kPrimaryPreferred : storages::mongo::options::ReadPreference
• kSecondary : storages::mongo::options::ReadPreference
• kSecondaryPreferred : storages::mongo::options::ReadPreference
• kUnacknowledged : storages::mongo::options::WriteConcern