Payment Certificate  issued by the principal agent on authority from the employer enabling the contractor to obtain a court order to enforce payment from the employer – also applies to a n/s subcontract advice in favour of a subcontractor, issued by the contractor. Where a creditor possesses a liquid document, in which in which the debtor acknowledges or is in law deemed to have acknowledged his indebtedness to the creditor in a fixed and determinate sum of money – the creditor may apply to court for provisional sentence for recovery of money due to him without his having to resort to litigation