code: function MarcIsoReader(options) {
    if (!(this instanceof MarcIsoReader)) {
      return new MarcIsoReader(options);
    }
  
    // File with records in ISO2709 format.
    this.recordsFile = null;
    // Buffer for the record (maximum size of the ISO2709 record is 99999 bytes).
    this.recordBuffer = new Buffer(100000);
    // Flag is true when next() can be performed.
    this.readyToRead = false;
  
    // File options.
    options = options || {};
    this.options = {
      // MARC format variation (MARC21, UNIMARC).
      format: (options.format || 'UNIMARC').toUpperCase(),
      // Input data encoding.
      encoding: options.encoding || null,
      // Permissive mode (ignore minor errors).
      permissive: options.permissive || false,
      // Template of the control field tag.
      controlFieldRegexp: options.controlFieldRegexp || /^00[1-9]$/
    }
  }
docs: /*
  The constructor of MARC ISO2709 reader.