Tribo, you wrote:
"Did your last two airliners distinguish between
- Poor as reported estimated surface friction/braking action or
- Poor as a measured or calculated coefficient (friction number)?"
1 expressly prohibited landing anytime reported braking action was poor - either by runway coefficient or by braking action.
The other specifies that landings will not be made on runways with more than one half inch of standing water, slush, or wet snow. It further goes on to provide a table regulating the maximum landing crosswind based on Reported Braking Action (Good, Good-Medium, Medium, Medium-Poor, Poor), Reported Runway Coefficient & Equivalent Runway Condition (Dry/damp/wet, slush/dry snow or wet snow/standing water/hydroplaning risk).
I would add, however, that neither of these two airlines operate routinely in severe icing conditions.
Hope this helps.