I have recently seen a very "light-weight" contract from a respectable company where the confidentiality clause essentially stated that the employee was subject to confidentiality with regard to everything about "all business matters and confidential information" and that this applied indefinitely beyond the termination of the contract.
I understand the reasons for confidentiality statements, but if the employee in question is a researcher or consultant, where the primary marketable skill is the know-how, the above statement essentially cripples the person from moving to a different company without breaching the agreement.
Now, I get that there is a big difference between know-how (like how a model is built) and trade secrets (the source code for building that model) but the formulation above leaves a lot of leeway in interpretation.
It's likely these matters are subject to variation from country to country but are there general rules that apply? What kind of considerations are there when deciding what is a "business matter" or "confidential info"? Shouldn't they be explicitly stated?