Client booking rules are used to control how many times a client can make a booking for the same time slot.
This is the default setting. Setting client constraints to None allows a client to book multiple resources at the same time. Unlimited bookings can be made in a time slot for the same or different resources. Businesses that need to allocate multiple resources per time slot to complete their service offering would set client constraints to None.
One booking per time slot
When Client Constraints are set to One booking per time slot if a client attempts to make an additional booking for any resource in the same time slot the booking will not be allowed. A message will be displayed indicating the client already has a booking for that time slot.