When a worker uses Find Appointment or a client uses Online Booking, there is an option to select a specific worker or select "Any Worker" to perform the service.  If "Any Worker" is selected,  a ~ before the worker's name on the Appointment Detail page.  Alternatively, if they requested a specific worker, the ~ symbol will not display.

To view if a worker was requested or if the Any Worker option was selected:

In this example below, Caroline Martin (client) requested Maria M for her Blow Dry but did not request a specific worker for her Manicure.