A synchronization group is a group of related MBOs. A mobile application can have predefined synchronization groups. An implicit default synchronization group includes all the MBOs that are not in any other synchronization group.
Two synchronization methods are provided in the package database class. You can synchronize a specified group of MBOs using the synchronization group name:
<PkgName>DB.synchronize(“sync_group”);
Or, you can synchronize all synchronization groups:
<PkgName>DB.synchronize();