According to Andrew (Help Desk) they likely should be supported.
According to msherry in IRC, the main reason the cards are not supported is that at 19 digits they are longer than Balanced's validation allows (only 14-16).
It's possible that at least some UnionPay cards do not pass the Luhn check ([1], [2]) but I can't find anything especially definitive on that topic.
According to Andrew (Help Desk) they likely should be supported.
According to
msherryin IRC, the main reason the cards are not supported is that at 19 digits they are longer than Balanced's validation allows (only 14-16).It's possible that at least some UnionPay cards do not pass the Luhn check ([1], [2]) but I can't find anything especially definitive on that topic.
1: http://en.wikipedia.org/wiki/Bank_card_number 2: https://code.google.com/p/chromium/issues/detail?id=242274