isSpecialNorthAmericanChar_(b1, b2) {
    // The bytes take the following form:
    // b1 -> |0|0|0|1|C|0|0|1|
    // b2 -> |0|0|1|1|  CHAR |
    return ((b1 & 0xf7) === 0x11) && ((b2 & 0xf0) === 0x30);
  }
Checks if the character is in the Special North American char. set.
@param {number} b1 Byte 1.
@param {number} b2 Byte 2.
@return {boolean}
@private