 Protocol ossification

Protocol ossification occurs when deployed implementations or intermediaries make established behaviour difficult to change, for example by rejecting an unfamiliar transport format or assuming fields will never evolve. Endpoint support alone may then be insufficient for deployment over real paths.^[ref]

Protocol ossification refers to a situation in the design and implementation of communication protocols where certain aspects become rigid and unchangeable over time. This rigidity can occur due to a number of factors, often leading to challenges in adapting protocols to new requirements or innovations.