private static int getThirdDigit(AdvancedFace bottom) {
		int thirdDigit = -1;
		int innerBounds = bottom.getFaceInnerBound().size();
		if (innerBounds == 0) {
			thirdDigit = 0;
		} else if (innerBounds == 1) {
			if (bottom.getFaceInnerBound().get(0).areAdjacentsXZOriented()) {
				thirdDigit = 1;
				print("one principal bore");
			}
		} else if (innerBounds == 2) {
			boolean res = true;
			for (FaceBoundAbstract faceBound : bottom.getFaceInnerBound()) {
				res &= faceBound.areAdjacentsXZOriented();
			}
			if (res) {
				thirdDigit = 4;
				print("two principal bores, parallel");							
			}
		} else if (innerBounds > 2) {
			boolean res = true;
			for (FaceBoundAbstract faceBound : bottom.getFaceInnerBound()) {
				res &= faceBound.areAdjacentsXZOriented();
			}
			if (res) {
				thirdDigit = 5;
				print("several principal bores, parallel");							
			} else {
				thirdDigit = 6;
				print("several principal bores, non parallel");
			}
		} else {
			thirdDigit = 9;
		}
		return thirdDigit;
	}