Legally speaking, a contract need not be in writing. But as regards contract of employment, there has to be an offer of appointment which is unconditionally accepted by the other party, both in written form. An affidavit does not add any evidentiary value. Affidavit only serves the purpose, that the deponent (the swearer of affidavit) has been identified by the person named therein and the notary is attesting to the signature as having been made in his presence, it offers no proof of its contents. So a valid contract can be formed by exchange of two pieces of paper, one mentioning the details of the offer made and the other conveying its unconditional acceptance.