TRYTN will treat a string passed in the src URL parameter as special and attach this value of the parameter to any booking that was made by a customer. This allows you to track purchase paths for third-party websites, OTAs, even multiple internal sites. The possibilities are endless. 

For regular booking links simply append the src parameter and desired value and when a user adds a product to their cart it will automatically attach. For the embedded flow you need to have the src parameter appended to the link they entered from to attach.