What is "sulloniacis"

Sulloniacis or Sulloniacae is the name of a place in Roman Britain which is known only from an entry in the Antonine Itinerary, a listing of routes and facilities for the cursus publicus, the official courier service of the Roman Empire. Iter (Itinerary) II of the British section runs between Richborough (Portus Ritupis) and Chester (Deva), and this shows Sulloniacis on the road now known as Watling Street, nine Roman miles from St Albans (Verulamium) and 12 from London. Sulloniacis is usually identified with Roman remains found at Brockley Hill near Edgware in the London Borough of Barnet.