switch {
	case !f.And.isEmpty():
		if err := e.EncodeElement(f.And, xml.StartElement{Name: xml.Name{Local: "And"}}); err != nil {
			return err
		}
	case !f.Tag.IsEmpty():
		if err := e.EncodeElement(f.Tag, xml.StartElement{Name: xml.Name{Local: "Tag"}}); err != nil {
			return err
		}
	default:
		// Always print Prefix field when both And & Tag are empty

	*p = Prefix{string: s, set: true}
	return nil
}

// MarshalXML - decodes XML data.
func (p Prefix) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if !p.set {
		return nil
	}
	return e.EncodeElement(p.string, startElement)
}

// String returns the prefix string
func (p Prefix) String() string {
	return p.string

	if err := e.EncodeToken(start); err != nil {
		return err
	}
	if err := e.EncodeElement(d.String(), xml.StartElement{Name: xml.Name{Local: "Bucket"}}); err != nil {
		return err
	}
	if d.StorageClass != "" {
		if err := e.EncodeElement(d.StorageClass, xml.StartElement{Name: xml.Name{Local: "StorageClass"}}); err != nil {
			return err
		}
	}

// encodes empty string otherwise
func (eDays ExpirationDays) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if eDays == 0 {
		return nil
	}
	return e.EncodeElement(int(eDays), startElement)
}

// ExpirationDate is a embedded type containing time.Time to unmarshal
// Date in Expiration
type ExpirationDate struct {
	time.Time
}

func (de DelMarkerExpiration) MarshalXML(enc *xml.Encoder, start xml.StartElement) error {
	if de.Empty() {
		return nil
	}

	type delMarkerExpiration DelMarkerExpiration
	return enc.EncodeElement(delMarkerExpiration(de), start)
}

// NextDue returns upcoming DelMarkerExpiration date for obj if
// applicable, returns false otherwise.
func (de DelMarkerExpiration) NextDue(obj ObjectOpts) (time.Time, bool) {

// empty string otherwise
func (t DeleteMarkerMTime) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if t.Time.IsZero() {
		return nil
	}
	return e.EncodeElement(t.Time.Format(time.RFC3339), startElement)
}

// ObjectV object version key/versionId
type ObjectV struct {
	ObjectName string `xml:"Key"`
	VersionID  string `xml:"VersionId"`
}

	case PrefixManyFolders:
		return "s3:Scanner:BigPrefix"
	}

	return ""
}

// MarshalXML - encodes to XML data.
func (name Name) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
	return e.EncodeElement(name.String(), start)
}

// UnmarshalXML - decodes XML data.
func (name *Name) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
	var s string
	if err := d.DecodeElement(&s, &start); err != nil {

// empty string otherwise
func (rDate RetentionDate) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
	if rDate.IsZero() {
		return nil
	}
	return e.EncodeElement(amztime.ISO8601Format(rDate.Time), startElement)
}

// ObjectRetention specified in
// https://docs.aws.amazon.com/AmazonS3/latest/API/API_PutObjectRetention.html
type ObjectRetention struct {

	if o.isDeleteMarker {
		start.Name.Local = "DeleteMarker"
	} else {
		start.Name.Local = "Version"
	}
	type objectVersionWrapper ObjectVersion
	return e.EncodeElement(objectVersionWrapper(o), start)
}

// DeleteMarkerVersion container for delete marker metadata
type DeleteMarkerVersion struct {
	Key          string