If the captain of a team disagrees with the interpretation of the rules by one of the referees, he may protest to the first referee. This must take place immediately after the decision. The first referee must accept the protest.
At the end of the match, the captain can record his protest in the scoresheet under "Remarks". This report must be signed by the first referee and the captain. A protest cannot be recorded after the end of the match if there has not been an indication by the captain during the match.
In/Out or touch decisions are not interpretations of the rule and, therefore, cannot be subject of a protest!
A team may protest, for example, if the first referee calls a fault and justifies it by saying that "the libero in may not complete an attack lower than the top of the net from the front zone".