doc.go

// parse FcCompressed (section 2.9.73)
func parseFcCompressed(fcData []byte) *fcCompressed {
	fCompressed := fcData[3]&64 == 64        // check fcompressed value (second bit from lestmost of the last byte in fcdata)
	fcData[3] = fcData[3] & 63               // clear the fcompressed value from data
	fc := binary.LittleEndian.Uint32(fcData) // word doc generally uses little endian order (1.3.7)
	return &fcCompressed{fc: int(fc), fCompressed: fCompressed}
}

Actually found someone else manually parsing .doc files. Thanks for confirming it's &64 == 64 for fCompressed. :)