code: function encodeSoftLineBreak(size) {
      // (Soft Line Breaks) The Quoted-Printable encoding
      // REQUIRES that encoded lines be no more than 76
      // characters long.
      if (line + size >= 76 && !qEncoding) {
        target[targetIndex++] = 61; // =
        target[targetIndex++] = 13; // \r
        target[targetIndex++] = 10; // \n
        line = 0;
      }
      line += size;
    }
docs: Regarding non-qEncoding: We do not use "_" as a literal since some decoders may decode this as " ". Instead, we represent "_" using "=5F".