The seventeen points fall into five major regions:
1. Jawf: the open oral/pharyngeal cavity — one point.
2. Halq: three regions of the throat — three points.
3. Lisan: distinct tongue positions and their opposing surfaces — ten points.
4. Shafatan: the lower lip and both lips — two points.
5. Khayshum: the nasal passage for ghunnah — one point.
Hence 1 + 3 + 10 + 2 + 1 = 17. A shared broad region does not mean that the detailed articulation of its letters is identical.