When using the islandora_marcxml module the MARCXML is not stored and uses the LoC transform to generate MODS. This allows the user to upload a new copy of the MARCXML and have the MODS be transformed again.
As a user I want to be able to upload a new copy of MARCXML for an object from an external source (WorldCat/ oXygen / whatever) and have the MODS transformed again and saved.
Provide a form to allow the user to upload a new MARCXML file and it have it be transformed to MODS.
Ingest an object with metadata created using the "MARCXML" ingest step.
Go to the datastreams page for that object.
Click the edit link that appears beside the MODS datastream.
Select "Update MODS from MARCXML"
Upload a new MARCXML file.
Ensure that a newly transformed version of the MODS is stored on the object.