The Compagnie in Java had an iron-clad rule.

For his protection, the family established one iron-clad rule: Bo was never to be left alone.

The application is extremely unusual, Ms. Henry said, because it violates two nearly iron-clad rules at the landmark commission.

It is an iron-clad rule of space, however, that operating pilots must be young.

The only iron-clad rule was that there were to be no food fights.

Yes, she shares her prototype's reliance on iron-clad rules and the belief that whatever she says is correct because she says it.

It was an iron-clad rule with him.

And the Compagnie had another iron-clad rule.

She-" It was an iron-clad rule of Salomon van der Merwe's never to permit any man to be alone with his daughter.

This is an iron-clad rule in polite society.