https://userapps.support.sap.com/sap/support/knowledge/en/3621590
3621590 - The value in field XREF1_HD cannot be converted to uppercase letters in...
When a document is posted with BAPI_ACC_DOCUMENT_POST, the value of field XREF1_HD is set with EXTENSION2. The value of field XREF1_HD is not automatically...
https://userapps.support.sap.com/sap/support/knowledge/en/3572350
3572350 - How to fill XREF1, XREF2 and/ or XREF3 values for FI documents posted by Logistical...
You post a FI document via MIRO and documents do not contain XREF1, XREF2 or XREF3 values filled.
https://userapps.support.sap.com/sap/support/knowledge/en/2515221
2515221 - Cannot add XREF1_HD and XREF2_HD during parking | SAP Knowledge Base Article
You cannot add the field XREF2_HD when you park a document.
https://userapps.support.sap.com/sap/support/knowledge/en/2945995
2945995 - XREF1, XREF2 and XREF3 are not updated/filled after bank statement file return is...
Fields BSEG-XREF1, BSEG-XREF2, and BSEG-XREF3 are not updated after upload bank statment file at Brazilian scenarios.