Dog Control Bill [HL]

My Lords, I do not want to turn this debate into a drafting session, but there is a phrase in this amendment that I do not think that I have ever seen before. It says that, "““the appropriate national authority, local authority or police authority is to satisfy itself””." I have seen wording saying that something ““must”” satisfy itself or that it ““could”” satisfy itself—I have even seen the words ““should”” satisfy itself—but I have never seen, ““is to satisfy itself””. I wonder what it means.