Totally going to signal boost you! This is an excellent thread. In the U.S., it really does vary state to state, but most will default to the Uniform Commercial Code (UCC). This is where a good contract attorney comes in handy.

In the U.S., if you do not memorialize it in the contract, you may find that the unspecified term defaults to whatever "standard" is in the UCC. Basically, get everything you can in the contract up-front, because the UCC may not be on your side.

The good thing about most attorneys in the U.S. is that almost all law schools require a full year of Contracts, and it is a subject featured on every state's Bar Exam. Basically, you have to know at least the basics of contract law to even get licensed.