Attribute extension generation to IDOC message type CRMXIF_IBASE_SAVE_M

Various attributes have been defined and assigned to a set type using tcode COMM_ATTRSET. The set type includes an entry in field CDB Table CDBD_ATTRVAL. The Create API Append has been checked when including in a transport which generated the API append structure for the set type. The set type has been assigned to a Category via tcode COMM_HIERARCHY.

We are planning to use IDOC message type CRMXIF_IBASE_SAVE_M for the legacy data migration. How do we include the new attributes?