Send custom instructions (or fields) to Google Checkout

Question

Is there a way to add a "Notes" or "Delivery Instructions" field to a Google Checkout post? I'm using the Custom Cart HTML API and it's worked out great so far except that I want to include a section for the buyer to add notes about the delivery.

Answer 1

^{Of course after I post the question I find the answer.}

Google offers tags to indicate that you want to add gift or special instructions at checkout. This Gift Messaging API can be used to allow a Gift or other message to be included, as well as allowing you to pre-fill it with input from the customer.

<input type="hidden" name="shopping-cart.buyer-messages.special-instructions-1" value="" />