We are updating our API to make it more easy to distinguish between what is a Product ID and what is an order ID 
. These changes might require action on your part.
If you use Order Hook URL for your Payment Buttons / Payment URLs / Widgets or for programmatically generated Temp Products you will need to update your code.
We will change all references to orders in our API from uuid to order_id.
We have set a migration period of two weeks during which we will send both uuid and order_id in the hook callbacks to give time to prepare 
The migration period will end on February 19th. Afterwards only order_id is used.
The important changes
Order Hook URL
These are the callbacks sent to your server if you have set them up. Unique identifier will change from uuid to order_id. During the migration period we will send both uuid and order_id.
Old code:
<OrderHook_URL>?status=2&uuid=2b0c7e2cd523458098b2
During migration:
<OrderHook_URL>?status=2&uuid=2b0c7e2cd523458098b2&order_id=2b0c7e2cd523458098b2
New code (after Feb 19th):
<OrderHook_URL>?status=2&order_id=2b0c7e2cd523458098b2
GET /api/merchant_order and GET /api/merchant_orders
Functionally calling these API points won’t change. The API documentation will reference order_id but your code won’t need changes.
GET /api/merchant_order/<order_id>
GET /api/merchant_orders?limit=<number>
The results from these calls use order_id instead of uuid.
Conclusion
As always the up to date documentation can be found from our website Blockchain API | Bitcoin API - Blockonomics.
Please let us know of any comments or concerns you may have. Thank you! 