mongodb/specifications — pull request #11 by ajdavis (2014-09-22 17:47:59+00:00)
Title: Add wire protocol compatibility info to TopologyDescription.

This is just a suggestion for how a client might track the wire protocol compatibility of the servers. None of the data structures or pseudocode in the spec is prescriptive, they're just a shorthand way to describe the *behavior* that the spec mandates.