// DeleteMarker cannot be specified if date or dates are specified.
	if (!e.IsDaysNull() || !e.IsDateNull()) && e.DeleteMarker.set {
		return errLifecycleInvalidDeleteMarker
	}

	if !e.DeleteMarker.set && !e.DeleteAll.set && e.IsDaysNull() && e.IsDateNull() {
		return errXMLNotWellFormed
	}

	// Both expiration days and date are specified
	if !e.IsDaysNull() && !e.IsDateNull() {
		return errLifecycleInvalidExpiration
	}

}

// IsNull returns if both NoncurrentDays and NoncurrentVersions are empty
func (n NoncurrentVersionExpiration) IsNull() bool {
	return n.IsDaysNull() && n.NewerNoncurrentVersions == 0
}

// IsDaysNull returns true if days field is null
func (n NoncurrentVersionExpiration) IsDaysNull() bool {
	return n.NoncurrentDays == ExpirationDays(0)
}

// Validate returns an error with wrong value