| NI-NXII | first to twelfth cranial nerves |
|---|---|
| P1, | P-one first parental generation |
| PI | first meiotic prophase; isoelectric point; pacing impulse; package insert; pancreatic insufficiency;... |
| S1-S5 | first to fifth sacral nerves |
| S1-S4 | first to fourth heart sounds |