While many items can be booked with a reference to exact times, inventory items^M and staff items^M need some sort of time reference. The booking times may or may not affect invoicing.

1. Stay on the  General tab and enable a time reference in the middle column underneath the input fields for units.
2. To book an item either by the hour or per unit, select Time reference optional. The entry of booking times is possible but not obligatory. When the item is booked for an event, the specified hourly price is multiplied in the event segment by the number of hours (count 2 in the segment).
   Ex.: Beamer
3. To always book an item per hour, select Time reference mandatory. When the item is booked for an event, the times of the event or event segment are automatically copied to the item, but can be changed manually. The specified hourly price is multiplied by the number of hours (count 2 in the segment).
   Example: Service staff per hour
4. To always book an item per unit, select Time reference flat rate. Entering booking times will still be possible, but not mandatory. The booking times will be reflected in inventory availability checks, but will not affect prices.
   Example: A technician is invoiced to the client at a flat rate of € 280.00 per day. The actual work time in hours is only given as information.