The PREAMBLE, the first part of the radiogram, consists of 8 parts: Number, Precedence, Handling Instructions, Station of Origin, Check, Place of Origin, and Month/Day Filed.
The 2nd item in the Preamble is the PRECEDENCE. This indicates how the message should be handled:
EMERGENCY - always spelled out. This is for any message "having life and death urgency".
Priority (P) - an important message or official message
Welfare (W) - an inquiry as to the health and welfare of an individual.
Routine (R) - the most common type of message (and the only type of message I have ever passed)
Exercise Messages (TEST) - a message passed for test or exercise purposes
Service (SVC) - indicates a service message "sent between stations" regarding message handling. According to ARRL literature, SVC is not a precedence.