Rule Interpretation?

[officialtony]

In studying this years test at an officials meeting, the question was "is it illegal alignment if the RF on Team R has one hand touching the floor on and over the centerline at the moment of serve? " I thought it was OK for the hand to be over the centerline and touching the floor as long as the hand was touching the centerline too. Please advise and offer the ruling in the book if you know it. Our state rules interpreter says it IS illegal ( OHIO ).