package encoding/xml
Unmarshaler is the interface implemented by objects that can unmarshal an XML element description of themselves.
UnmarshalXML decodes a single XML element beginning with the given start element. If it returns an error, the outer call to Unmarshal stops and returns that error. UnmarshalXML must consume exactly one XML element. One common implementation strategy is to unmarshal into a separate value with a layout matching the expected XML using d(1st parameter).DecodeElement, and then to copy the data from that value into the receiver. Another common strategy is to use d.Token to process the XML object one token at a time. UnmarshalXML may not use d.RawToken.
Golang encoding/xml.Unmarshaler type usage example
unmarshalerType = reflect.TypeOf((*Unmarshaler)(nil)).Elem()
Reference :
http://golang.org/pkg/encoding/xml/#Unmarshaler
