Belgian Congo. 1917. Registered envelope written from Dodouna addressed to France bearing Yvert 28, 5c green, Yvert 29, 10c red, Yvert 30, 15c turquoise and Yvert 31, 25c blue tied by ' B.P.C.V.P.K. No18' double ring with registered label, routed via Dar-es-Salem with London registered transit.Nice item of occupation mail.