Murray Goodman:Do you sometimes feel you’re speaking a different language to your colleagues? When it comes to the topics of Class of Service (CoS) and Quality of Service (QoS) I’m often left dumbfounded that there is so much confusion around these terms. Although I must confess, I too have had my own views that turned out not to be entirely correct – particularly how they relate or work together. Over time these definitions seem to have become more blurred and are now often used interchangeably.