for a single message bundle that is too big - The server will decide what to do ( e.g.,  - ambiguous in base spec  - sender will get a failure)  add guidance to the effect that the implementers should consider message bundle size when creating a profile to decide what to include in the bundle to avoid large file size errors. for multiple message bundles - this is a future issue for batch messages and will need to address. (see how paging and subscriptions work as a guide)   Additionally, consider an update to IG quality criteria to ensure that FHIR IGs using messaging or messaging-like exchange patterns address: message size.