For a given surname it is easy to find many variations in its coats of arms*. I get the impression that coats of arms were described in records as text and thus were open to interpretation at the time they are rendered. Is this true, or are there actual interpretations of such descriptions that are more official than others?
*I realize surnames may have differing coats (e.g., the same surname having different coats from Ireland v. England.) What I am interested to know is for a specific coat of arms is one rendering the authoritative version versus another?