How we can populate TaxClassificationCode when we import cXML invoices from OBN

Summary:

We are importing supplier cXML invoices via OBN and currently each invoice line is being created with STANDARD tax classification code, due to the PO line containing the same code and that being the default against the supplier. However, some of the invoice lines being imported are Zero rated and so the tax lines should automatically be created with the ZERO tax classification code, which they are not currently and this is causing invoice holds

This behaviour was working when using the OAG invoice format but we can't get it to work with cXML.

Is anyone able to confirm what needs to be updated in the xsl to capture the TaxClassificationCode?