(1) A person "enters or remains unlawfully" in or upon premises when he is not privileged or licensed to do so.
(2) A person who, regardless of his intent, enters or remains in or upon premises which are at the time open to the public does so with license or privilege unless he defies a lawful order not to enter or remain personally communicated to him by the owner of such premises or other authorized person.
(3) A license or privilege to enter or remain in or upon premises which are only partly open to the public is not a license or privilege to enter or remain in or upon a part of the premises which is not open to the public.
(4) A person who enters or remains upon unimproved and apparently unused land which is neither fenced nor otherwise enclosed does not commit criminal trespass unless notice against trespass is personally communicated to him by the owner of the land or some other authorized person or unless notice is given by posting in a conspicuous manner.
(5) Private land adjoining a railtrail that is neither fenced nor otherwise enclosed shall be presumed to be land where notice against trespassing has been given by the owner of the land, and a person utilizing the railtrail shall be presumed to lack privilege or license to enter upon that land unless the person has permission from an adjoining landowner to do so.