+Receipt number of this transaction; this is actually a string, unique to all
+InternetSecure transactions.
+
+=item sales_number()
+
+Sales order number of this transaction. This is a number, unique to each
+merchant, which is incremented by 1 each time.
+
+=item date()
+
+Date and time of the transaction. Format is C<YYYY/MM/DD hh:mm:ss>.