if paxKey == paxNone {
				whyNoPAX = fmt.Sprintf("PAX cannot encode %s=%v", name, ts)
				format.mustNotBe(FormatPAX)
			} else {
				paxHdrs[paxKey] = formatPAXTime(ts)
			}
		}
		if v, ok := h.PAXRecords[paxKey]; ok && v == formatPAXTime(ts) {
			paxHdrs[paxKey] = v
		}
	}

	// Check basic fields.
	var blk block
	v7 := blk.toV7()
	ustar := blk.toUSTAR()
	gnu := blk.toGNU()