Cepheid luminosity versus log P/Q for 5, 7 and 9 M_⊙ models in the second (solid lines) and third (dashed lines) crossings. Rotating models with ω = 0.5 are shown in black, non-rotating models in gray. At a given value of log P/Q, log L can easily vary by more than 0.1 dex (25%), depending on ω as well as the crossing number. Hence, rotation leads to an intrinsic dispersion of the period−luminosity relationship.