Comment by hakfoo

For some reason, a lot of credit card processing APIs are still oriented around physical card machines, so they have a lot of fields devoted to self-declaration of the available features.

Some of the APIs allow the machine to say "I can accept a PIN up to 12 digits".

However, I don't know if anyone 1) actually delivered on it and 2) how you'd know in advance just poking random devices in stores.