Not able to answer your question except to say that apud in Latin means among, and the statement means, I think, that the charter was made or given by Henry de St Clair, Earl of Orkney. By coincidence, I have just returned a book to our local library about the same Henry de St Clair, a scholarly study of evidence he says he uncovered which shows St Clair (the ancestor of the Sinclair family) gathered a crew to sail across the Atlantic, and that they landed in what is now Nova Scotia and explored that area over 100 years before Columbus sailed. Quite convincing. Blake Allan