// does not always result in the PAX format being chosen, which
	// causes a 1KiB increase to every header.
	if tw.hdr.Format == FormatUnknown {
		tw.hdr.ModTime = tw.hdr.ModTime.Round(time.Second)
		tw.hdr.AccessTime = time.Time{}
		tw.hdr.ChangeTime = time.Time{}
	}

	allowedFormats, paxHdrs, err := tw.hdr.allowedFormats()
	switch {
	case allowedFormats.has(FormatUSTAR):
		tw.err = tw.writeUSTARHeader(&tw.hdr)
		return tw.err

		i += size
		// Officially, ZIP uses CP-437, but many readers use the system's
		// local character encoding. Most encoding are compatible with a large
		// subset of CP-437, which itself is ASCII-like.
		//
		// Forbid 0x7e and 0x5c since EUC-KR and Shift-JIS replace those
		// characters with localized currency and overline characters.
		if r < 0x20 || r > 0x7d || r == 0x5c {