I worked on a IDOC to File scenario.
An IDoc ORDERS.ORDERS05 created for Create/Update/Delete Purchase order at ME21N.
File expects Different format of file for each create/update/delete.
Multimapping is helpful here.
@Message mapping-target side, 3 xsd are added each corresponds to Create/update/delete.
A condition kept in the graphical mapping to map the IDOC to one xsd among the three at runtime.
reg, avinash