Spin inference from magnetic-dipole hyperfine intervals

Consecutive positive gaps obey ${\nu }_F=|A|F/h$ for an isolated hyperfine multiplet governed by the magnetic-dipole hyperfine interaction. Their common difference estimates $|A|/h$, and the first gap divided by that scale identifies the first higher F. The endpoints of the resulting F ladder constrain I and J. Gap magnitudes alone do not fix the sign of A or an absolute nuclear g-factor.