Fill your initials in the boxes for times you CAN attend a meeting. TIMES ARE IN UTC. Assume that the meeting time will change to accommodate Daylight Savings Time. A user in italics has an occasional conflict at that time, thus it is not preferred but can work if it is the only slot available. If you wish to indicate the current meeting time, make that entry bold.
At the top and bottom of the matrix, include a list of users. This makes deciphering the matrix easier for organizers and other attendees.