Will be moving to the https://build.fhir.org/async-bundle.html pattern for polling, so will rewrite the section on polling ( https://build.fhir.org/ig/HL7/davinci-pct/formal_specification.html#polling ) based on that.  Note that the async pattern does not specify a fixed interval between polling tries. Rather, each payer system will have the ability to communicate when to poll next via the Retry-After HTTP header, thus if a GFE is simple to process they can specify a short interval like a few minutes, but if something requires a longer timeframe, they can say try back in a longer time frame. However, will document that there is an industry goal to shorten timeframes, and given the tight timelines required by the NSA it is in everyone's best interest for the industry to attempt quick turnaround times.  Also we will not tackle Subscription until phase 2 since it will change dramatically in R5, and I we don't plan to move to FHIR R4B and the new Subscription backport IG in phase 1. When copying the async pattern info, make sure that we flag the response codes as SHALL. For instance "HTTP Status Code of 202 Accepted" will become "SHALL respond with HTTP Status Code of 202 Accepted".  Once written, will review the adaptation of the async pattern with the public stakeholder group for PCT.