The Challenge referee carries out his/her functions in the challenge booth located in a separate position determined by the FIVB Technical Delegate.
25.2.1 He/she supervises the challenge process and ensures that it proceeds according to the challenge regulation in force.
25.2.2 The Challenge referee shall wear an official referee uniform while performing his/her functions
25.2.3 After the challenge process he/she advises the first referee of the nature of the fault
25.2.4 At the end of the match, he/she signs the score sheet