_isRpnOrNrpnController(controller) {

    return controller === 6 ||
      controller === 38 ||
      controller === 96 ||
      controller === 97 ||
      controller === 98 ||
      controller === 99 ||
      controller === 100 ||
      controller === 101;

  }
Indicates whether the specified controller can be part of an RPN or NRPN sequence
@param controller
@returns {boolean}
@private