Comparing info between rows and columns

The expected output is the same file with the errors marked. So I can send it back and ask them to fix it.

types of error that can happen are:

A person can be connected to either one or multiple locations but they always have the same contracts.

Only one contract can be in open status at a time, and it has to be open in all locations.

A contract can only appear once per location(I have a case that someon has contract A twice- once open, once close)

The date for a contract is the same in all locations.

an open contract can't have an earlier date then a closed one. 

"null" values are an error.

Contracts have order- Contract B can only happen when contract A closes, not the other way around. 

That's all that I can think of now.

What do you mean by " What are we doing to identify what is an error?"

Thank you