docs: function write_BrtCalcProp(data, o) {
  	if(!o) o = new_buf(26);
  	o.write_shift(4,0); /* force recalc */
  	o.write_shift(4,1);
  	o.write_shift(4,0);
  	write_Xnum(0, o);
  	o.write_shift(-4, 1023);
  	o.write_shift(1, 0x33);
  	o.write_shift(1, 0x00);
  	return o;
  }