There do not seem to be any fixed rules of engagement.

There are few fixed rules to cover such situations.

In other words, there is no fixed rule for book purchasing.

And games that lasted all day, with no fixed rules.

Our motto should be that there are no fixed rules.

There are no fixed rules about granting modern coats of arms.

There are no fixed rules about how to use bullets.

Usually there are fixed rules you can use to decide whether something is in canonical form.

Usually no fixed rules and specific contents are decided in advance.

They believed that China was too large to be governed by any single set of fixed rules or a legal bureaucracy.