Opinion as to usages, tenets, etc., when relevant
51.  When the court has to form an opinion as to —
(a)the usages and tenets of any body of men or family;
(b)the constitution and government of any religious or charitable foundation; or
(c)the meaning of words or terms used in particular districts or by particular classes of people,
the opinions of persons having special means of knowledge thereon are relevant facts.