[CW] AR or K after CQ?

[Roy]

"Turning it back to the other station,  AR hiscall DE yourcall KN.

End of contact, SK hiscall DE yourcall (followed by nothing if you don't
mind others calling you back, or CL if you are shutting down)."



All of my 'operating procedures' books list CW prosigns such as SK and AR as 
"end codes", obviously intended to be used at the ENDS of transmissions. Not 
within a transmission like the examples above. (?!)

73,   Roy     K6XK