I recall reading about the history of the network that BBN inherited the calls WYFI on their first station in Norfolk, Virginia, and 'assigned' the meaning of "Where You'll Find Inspiration". When they bought their second station, WHPE in High Point--originally owned by the High Point Enterprise, they 're-assigned' the meaning as "Where His Praises Echo". By the time they bought their third station, the former WXNC in Henderson, they applied for the call letters WYFL with the meaning "Where You'll Find Love" and have largely stuck with requesting available "WYF_" calls and assigning a similar meaning. PBS North Carolina is another example of requesting available sequential call letters, in their case reflecting flagship WUNC-TV with the last letter changing; further down the alphabet indicating the order in which a transmitter was activated (WUNC-TV 1955, WUND-TV 1965, WUNE-TV 1971, et al).