Because many of the inscriptions on the Dieppe maps are written in French, Portuguese or Gallicised Portuguese, it has often been assumed that the Dieppe school of mapmakers were working from Portuguese sources that no longer exist. It has been assumed that Portuguese cartographers were bribed for information of the latest discoveries, despite the official Portuguese Politica de sigilo (policy of silence). The Cantino map of 1502 (not a Dieppe school map) shows evidence of second-hand Portuguese sources, and this has been taken by some as supporting evidence for this assumption.