+# from http://perl.about.com/compute/perl/library/nosearch/P073000.htm
+# verified by http://www.beachnet.com/~hstiles/cardtype.html
+# Card Type Prefix Length
+# MasterCard 51-55 16
+# VISA 4 13, 16
+# American Express (AMEX) 34, 37 15
+# Diners Club/Carte Blanche 300-305, 36, 38 14
+# enRoute 2014, 2149 15
+# Discover 6011 16
+# JCB 3 16
+# JCB 2131, 1800 15
+#
+# from Neale Banks <neale@lowendale.com.au>
+# According to a booklet I have from Westpac (an Aussie bank), a card number
+# starting with 5610 or 56022[1-5] is a BankCard
+# BankCards have exactly 16 digits.
+