Coupon event API change log

Here is a list of all updates to the Coupon Event API:

version 1.0.4
– Updated an event type

version 1.0.3
– Changed all signature calculations to SHA-2 256 variant (MD5/SHA-1 will continue to work for a time period)

version 1.0.2
– Listener functions now implemented
– Added callback function for listening on reports being generated

version 1.0.1
– Minor text changes