An experimental fork of marc21.
The main difference for now is that marc22 will be able to read MARC from MARCXML, whereas marc21 can only write XML.
marc21 uses a []Field interface slice to hold both control and data fields, which
will prevent XML parsing.
See http://golang.org/src/pkg/encoding/xml/read.go#L345:
...
345 case reflect.Interface:
346 // TODO: For now, simply ignore the field. In the near
347 // future we may choose to unmarshal the start
348 // element on it, if not nil.
349 return p.Skip()
...marc22 is a workaround for Go 1.3. The situation might improve with coming versions.