// other fields in Header take precedence over PAXRecords.
	PAXRecords map[string]string

	// Format specifies the format of the tar header.
	//
	// This is set by Reader.Next as a best-effort guess at the format.
	// Since the Reader liberally reads some non-compliant files,
	// it is possible for this to be FormatUnknown.
	//
	// If the format is unspecified when Writer.WriteHeader is called,

			// section; there must be a preceding call to handleRegularFile.
			if err := tr.handleSparseFile(hdr, rawHdr); err != nil {
				return nil, err
			}

			// Set the final guess at the format.
			if format.has(FormatUSTAR) && format.has(FormatPAX) {
				format.mayOnlyBe(FormatUSTAR)
			}
			hdr.Format = format
			return hdr, nil // This is a file, so stop
		}
	}
}