Dear Ivy,
In the below case the PR is updated with status 'Rejeceted'.
1. Create a PR in ECC and for the same SC is created in SRM.
2. Reject the items in SOCO, the Closed field is updated as 'X' in ECC,
3. Change the same PR in ECC, the Changes are send to SRM and updated.
4. The Confirmation XML message, which triggers for change is send from SRM to ECC is updated with Rejected.
Kindly check and confirm is it correct.