[A-Z]{1,5} # callsign letters (required)
(?:-(?:\d{1,2}))? # - nn possibly (eg G8BPQ-8)
(?:/[0-9A-Z]{1,7})? # / another prefix, callsign or special label (including /MM, /P as well as /EURO or /LGT) possibly
[A-Z]{1,5} # callsign letters (required)
(?:-(?:\d{1,2}))? # - nn possibly (eg G8BPQ-8)
(?:/[0-9A-Z]{1,7})? # / another prefix, callsign or special label (including /MM, /P as well as /EURO or /LGT) possibly