Only pencils should be available for swimmers to use to check in, so changes can be made if necessary Sharpies are for swimmers to write events on their hands.
Supervise swimmers during check-in. Swimmers do the following:
Check in using pencil
Initial next to their name
Circle event numbers they will swim
X and initial event numbers they will not swim
May write event numbers on their hands using a Sharpie
Swimmers can return to change which events they are swimming, as long as the events have not closed. To do this, they should thoroughly erase their mark, make a new mark, and initial it. (If a swimmer’s mark becomes illegible, make a note next to the swimmer's name, so it can be seen when the event is closed.)
Encourage swimmers to make lines in front of the check-in table instead of crowding.
Clearly indicate which lines go with which genders and age groups.
The current (2010) rules do not penalize a swimmer who fails to show up for an event when he is called to the blocks. He will get to swim the rest of his events; he will not have to return to check-in. However, the missed event does count for any limit on the total number of events.