# File MIME/types.rb, line 300
        def signature?
            case @content_type
                when "application/pgp-keys", "application/pgp",
                     "application/pgp-signature", "application/pkcs10",
                     "application/pkcs7-mime", "application/pkcs7-signature",
                     "text/vCard", "text/vcard"
                    true
            end
        end