From
a 2012 BBC article:
The
Professional Game Match Officials - the board responsible for providing the Premier League with officials and developing refereeing - provided BBC Sport with some answers.
How do referees keep track of how long an injury takes?
There's two people, one of the assistants and the fourth official. As soon as the physio or trainer comes on, they will monitor how long they are on the pitch.
Does he stop his watch or just note what time the injury has happened?
He doesn't stop his watch, no. It's just a case of monitoring their watch; they never stop the watch.
Is 30 seconds added on for each substitution?
As a rule of thumb, yes. But if a player is doddering, meandering, then extra time can be added. And it's the same for red cards, yellow cards as well.
Is the clock stopped for goals?
No, it's not. But they do add time (to cover celebrations). It's around 30 seconds as a rule of thumb, unless they spend five minutes celebrating. Every situation is different, they'll take each one on its merit.
How do referees account for time-wasting?
That's discretionary. It has to depend on the situation.
When does he let the fourth official know how long he wants added on?
It's usually about two minutes before the end of each half.
How does he keep track of the amount of added time in injury time itself?
That's the same process itself. For example in the Reading-Arsenal game there was a substitution in extra time.
Do referees not blow for full-time when a team is attacking?
No. They can blow for full time at any junction.
What have been the major changes in the process over recent years?
Just that fourth officials note down every stoppage of play. They can present it to the management team of any club - should they want a list.
How long have fourth officials been noting the times down?
It's actually since last season. They've been writing it down properly so that people can see this is the list of where the time has been added on.