Bake-offs refer to events where engineers get together to test their implementations against each other.
Implementations tested during the bake-off are prototypes.
Bake-offs are open to every developer. The time window for holding bake-offs is short as they take place within the time frame of the standards drafting. Test cases are written in prose. By defining one type of interoperability testing, namely bake-off, precisely, confusion is eliminated with other types of interoperability testing. Bake-offs have been around for many years, though less in the telecommunications world.