In recording type templates, an ! has to be used to blank a field out but in BAPI type templates we have to update the field to a true blank in order to send to SAP properly. This can't be done via excel and in order to do it from the page, every field would require a rule or drop down customization.
By using the mass change feature to enact the blank, one rule works on every template. Our current implementation is to accept literally 'Blank' and convert that to a true SQL blank.