Always confusion here, Airgus, but there are unfortunately a few 'friction measurement systems' in use, and I believe the method used SHOULD be specified on the report, but rarely is. I suspect
they are using the 'measured or calculated coefficient' table and 49 would be 'good', based on that actual given. You will see this table
here. NB if the action is
estimated it will be a single digit.
Where it all starts to get VERY interesting is when slippery time' arrives and you finish up having to make an intelligent guess which system has been used.
You will get a sense of the confusion
here too