The extremely short wavelengths recorded by a digital tape recorded meant that tape and tape transport cleanliness was an important issue. Specks of dust or dirt were large enough in relation to the signal wavelengths that contamination by such dirt could render a recording unplayable. Advanced digital error correction systems, without which the system would have been unworkable, still failed to cope with poorly maintained tape or recorders, and for this reason a number of tapes made in the early years of digital reel-to-reel recorders are now useless.