// Do nothing.
	case format.has(FormatGNU):
		copy(b.toGNU().magic(), magicGNU)
		copy(b.toGNU().version(), versionGNU)
	case format.has(formatSTAR):
		copy(b.toSTAR().magic(), magicUSTAR)
		copy(b.toSTAR().version(), versionUSTAR)
		copy(b.toSTAR().trailer(), trailerSTAR)
	case format.has(FormatUSTAR | FormatPAX):
		copy(b.toUSTAR().magic(), magicUSTAR)
		copy(b.toUSTAR().version(), versionUSTAR)
	default:

				nul(v7.modTime()) && nul(ustar.devMajor()) && nul(ustar.devMinor())) {
				hdr.Format = FormatUnknown // Numeric fields must end in NUL
			}
		case format.has(formatSTAR):
			star := tr.blk.toSTAR()
			prefix = p.parseString(star.prefix())
			hdr.AccessTime = time.Unix(p.parseNumeric(star.accessTime()), 0)
			hdr.ChangeTime = time.Unix(p.parseNumeric(star.changeTime()), 0)
		case format.has(FormatGNU):