The EXCHANGE_TYPE constants are used with the ExchangeType property of the SQLMerge object to specify whether merge replication changes should be uploaded to the Publisher, downloaded to the Subscriber, or both (uploaded and then downloaded).
|UPLOAD||1||Only merge Subscriber changes with the Publisher.|
|DOWNLOAD||2||Only merge Publisher changes with the Subscriber.|
|BIDIRECTIONAL||3||Merge all changes between the Publisher and Subscriber (default).|
You should use a BIDIRECTIONAL synchronization unless you have a specific reason for separating the UPLOAD and DOWNLOAD phases.