Absolute height SDS | For ages 0 to *p* years, refer if SDS < *a* |
*a*
| SDS referral level before age *p* | −2.5 | −1.5, −2, −2.5, −3, −3.5, −4 |

| For ages *p* to 10 years, refer if SDS < *b* |
*b*
| SDS referral level after age *p* | −2.5 | −1, −1.5, −2, −2.5, −3 |

| |
*p*
| Age (in years) at which the referral level changes | Unspecified | 1, 2, 3 |

Parental height corrected | For ages *q* to 10 years, refer if: |
*c*
| SDS cut off level below which SDS must lie | −1.3 | −1, −1.3, −1.5, −2, −2.5 |

| SDS < *c*, AND |
*d*
| Difference between target height SDS and SDS | −1.3 | −1, −1.3, −1.5, −2, −2.5 |

| SDS − THSDS < *d* |
*q*
| Age (in years) after which the rule is effective | 0, 3† | 1, 2, 3 |

Deflection | For any pair SDS_{1} and SDS_{2} measured at ages X_{1} and X_{2} (in years), refer if: | | | | |

| *r* ⩽ X_{1} < X_{2} < 10, AND |
*e*
| Minimal interval (in years) between X_{1} and X_{2} | 1‡ | 1, 2, 3 |

| X_{2}–X_{1} ⩾ *e*, AND |
*f*
| SDS cut off level below which SDS_{2} must lie | Unspecified | 10, 0, −1, −2, −2.5 |

| SDS_{2} < *f*, AND |
*g*
| Height velocity change in SDS per year | −0.25 | −0.20, −0.25,−0.33, −0.50 |

| (SDS_{2}–SDS_{1})/(X_{2}−X_{1}) < *g* |
*r*
| Age (in years) after which the rule is effective | 0, 3† | 3 |