Group Bookings contain a header element which provides an "at a glance" view of the critical information of the booking.
For Example, if you have allocated 13 Rooms for 4 nights, then the Projected Income would be $3,480.75 (incl. tax). However, are no rooms booked yet so the the Group Revenue is currently $0. When you add a booking to the Group, the Group Revenue amount increases.
If considering using the %%projected_income_and_charges%% for your Group Letters, read the 'Notes' section to learn about edits within bookings that are part of a Group.
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