That was supposed to be in the original CL, but missed
the files.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/
5570052
// The XML element for a struct contains marshalled elements for each of the
// exported fields of the struct, with these exceptions:
// - the XMLName field, described above, is omitted.
+// - a field with tag "-" is omitted.
// - a field with tag "name,attr" becomes an attribute with
// the given name in the XML element.
// - a field with tag ",attr" becomes an attribute with the
// of the above rules and the struct has a field with tag ",any",
// unmarshal maps the sub-element to that struct field.
//
+// * A struct field with tag "-" is never unmarshalled into.
+//
// Unmarshal maps an XML element to a string or []byte by saving the
// concatenation of that element's character data in the string or
// []byte. The saved []byte is never nil.