In a field where it says only to put your EIN, or in a field which says put either your EIN or SSN?

All the business card applications I've looked at (admittedly, only from a couple banks so far) have either had a field where it directs you to put in a SSN if you don't have an EIN, or have separate fields for EIN and SSN.

Please post a link of business card application which asks for an EIN, accepts an SSN in that field, yet says nothing on the application form indicating that an SSN can be entered in the EIN field. Only that would the equivalent of what you found on the Barclay personal card application, which was asking for an SSN, with no mention of EIN being an acceptable substitute.