When making assignments, you are provided a variety of information about an officials availability.

First, it is assumed that officials enter availability times based on the first game start time that they can accomodate.

When you see a number like -32 or + 10, that is giving you an indication of how tight that officials availability is to making it to the game. The more positive the number, the more margin the official has with making it on-time. The more negative the number, the more likely the official will be unable to make it on time. The calculation is : GameTime - AvailabilityTime - DrivingTime

Note the example below with a GAME TIME of 5:00 PM.

• The 1st listed official has no availability restriction that affects this game.
• The 2nd listed official is available starting at 4:00 PM and has a drive time of 50 minutes. Given the game time is at 5:00, that means the official has +10 minutes of margin to arrive at the game. 
• The 2nd to LAST listed official is available starting at 4:00 PM and has a drive time of 35 minutes. That gives that official +25 minutes of margin in arriving at that game.
• The last listed official is available starting at 5:00. With their drive being 24 minutes, that gives them a margin of -24 minutes in making it to the game. It might be difficult for that official to make it on time.