Set Transaction ID from WooCommerce/3rd party

I see there is a Transaction ID field when I export entries into CSV.

My guess is this would be set if I was using the PayPal add-on, but I'm using WooCommerce which actually runs the transactions through InfusionSoft via another plugin.

But basically the logic is going to be the same -- on the return trip from InfusionSoft, I can store the InfusionSoft Invoice ID in a variable, then I want to write that value into the Transaction ID.

That way, when we export the entries, I'll be able to look up an order via Transaction ID.

QUESTION -- can you direct me to the documentation that covers where the transaction ID hooks are so I can set this via my own customized code?

Thanks -that is what I was looking for. If you know @lucasstark who developed the WooCommerce plugin... ask him why this isn't already default behavior in his gravity forms woocommerce addon?

Seems silly to have the ability to collect information in the shopping cart, only to have no transactionID logged to figure out what info is real and what's from abandon cart sessions?

Further, it would be really nice to also have the add-on go back and delete out the abandoned cart forms.

I've posted on WooCommerce of course, but I'm not getting any response there.

Thank you for your time!