//
	// The following are semantically equivalent:
	//  h.Xattrs[key] = value
	//  h.PAXRecords["SCHILY.xattr."+key] = value
	//
	// When Writer.WriteHeader is called, the contents of Xattrs will take
	// precedence over those in PAXRecords.
	//
	// Deprecated: Use PAXRecords instead.
	Xattrs map[string]string

	// PAXRecords is a map of PAX extended header records.
	//

	var is1x0 bool
	major, minor := hdr.PAXRecords[paxGNUSparseMajor], hdr.PAXRecords[paxGNUSparseMinor]
	switch {
	case major == "0" && (minor == "0" || minor == "1"):
		is1x0 = false
	case major == "1" && minor == "0":
		is1x0 = true
	case major != "" || minor != "":
		return nil, nil // Unknown GNU sparse PAX version
	case hdr.PAXRecords[paxGNUSparseMap] != "":

		tests: []testFnc{
			testHeader{Header{
				Typeflag:   TypeXGlobalHeader,
				PAXRecords: map[string]string{"path": "global1", "mtime": "1500000000.0"},
			}, nil},
			testHeader{Header{
				Typeflag: TypeReg, Name: "file1",
			}, nil},
			testHeader{Header{
				Typeflag:   TypeReg,
				Name:       "file2",
				PAXRecords: map[string]string{"path": "file2"},
			}, nil},
			testHeader{Header{

	tw := NewWriter(&b)
	hdr := &Header{
		Name:       "file.txt",
		Uid:        1 << 21, // Too big for 8 octal digits
		Size:       int64(len(data)),
		ModTime:    time.Now().Round(time.Second),
		PAXRecords: map[string]string{"uid": "2097152"},
		Format:     FormatPAX,
		Typeflag:   TypeReg,
	}
	if err := tw.WriteHeader(hdr); err != nil {
		t.Fatalf("tw.WriteHeader: %v", err)
	}