principal moments of inertia

https://doi.org/10.1351/goldbook.P04848
Moments of inertia about the principal axes of the molecule chosen so as to make all the products of inertia equal to zero, IA ≤ IB ≤ IC.
Source:
Green Book, 2nd ed., p. 23 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)