The value of precedence field in IP header.
<255> Invalid value
<0-7> value of precedence
routine(0) Routine precedence
priority(1) Priority precedence
immediate(2) Immediate precedence
flash(3) Flash precedence
flash-override(4) Flash Override precedence
critical(5) Critical precedence
internet(6) Network Control precedence
network(7) Internetwork Control precedence