PROSIGNS AND OTHER PROCEDURAL SIGNALS  FOR MORSE CODE Prosigns are symbols formed by running together two characters into one without the intercharacter space) to make an abbreviation for the most common procedural signals. Usually written with a BAR over the characters. The ones in <  >  are considered by the ARRL as prosigns -- see ARRL page URL:

    End Of Line
  Full Stop
<AR>    End of message
<AS>    Stand by; wait
    Separation (break) between address and text; between text and signature.
    (Error in sending. 8 dits - Transmission continues with last word correctly sent.)
       Short form of above
    Repeat; I say again. (Difficult or unusual words or groups.)
    Number follows
    Out; clear (end of communications, no reply expected.)
 
The following without the <  > are other commonly used two letter procedural signals -- some Hams run them together -- others do not.

BK    Break
CL    Going off the air (clear)
CQ    Calling any amateur radio station (Many add a space between the C and the Q)
DE    This or From
KA    Beginning of message
KN    Go only, invite a specific station to transmit
VE    Understood (VE)
Commonly used in CW - single letter meanings
C      Correct yes
K      Go, invite any station to transmit
N      No Negative
R      All received OK