Proof of claim by operational creditors must be filed in Form B and proved by documents or information utility records. Operational creditors (excluding workmen or employees) must submit proof of claim to the liquidator using Form B of Schedule I, in person, by post, or electronically. Existence of the debt may be proved by records available with an information utility or by relevant documents including a supply contract with an invoice, a court or tribunal order on non-payment, or the corporate person's financial accounts.