SUM phase XPRAS_AIMMRG executes XCLAs (and XPRAs) during the downtime of a system conversion run.

If you are using the downtime-optimized conversion aproach, you have the option to select specific XCLAs to be processed in uptime. For more information about how to select appropriate XCLAs for the uptime processing and how to configure SUM for this approach, see SAP Note 2778832 .