
The time shown on the board is the minimum to be added on. So 4 minutes means 4.00 - 4.59 - assuming there are no extra stoppages/delays in that period. They will be added on at the referee's discretion and added to the time to be played without notification.
So, for instance, when we were at Cardiff 4 minutes were indicated to be added. In that 4th (last) minute there was an altercation lasting 3 minutes, so these 3 minutes were added onto the 4, and Bellamy scored in the 97th minute.
What is the problem in understanding this?