[bhouston]

Yes anything type of acknowledge that is reasonable can be viewed as agreement in Canada under law but to prove it, if there is a dispute, it is best to have it in some reproducible form.

For a contract you need an exhchange of value in both directions and an agreement. It can be completely verbal and enforceable if you can prove that both parties knowingly and reasonably consented to it.

I think the requirements for consent go up as the agreement becomes more exploitive/one sided though.