"4" -- No longer list routers that are not running in the consensus
"5" -- adds support for "w" and "p" lines.
"6" -- Prefers measured bandwidth values rather than advertised
+ "7" -- Provides keyword=integer pairs of consensus parameters
+ "8" -- Provides microdescriptor summaries
+ "9" -- Provides weights for selecting flagged routers in paths
Before generating a consensus, an authority must decide which consensus
method to use. To do this, it looks for the highest version number