The term 'Caller Foul' is used in sports to indicate when a player has committed a foul. The three letter acronym UMP stands for umpire, the three letter acronym REF stands for REFEREE, and the seven letter acronym REFEREE stands for the person responsible for making the call on the field. The four letter acronym AVON stands for the AVON Football Association, which is an organization that sets the rules and regulations for football.