Why should the assessment of a casual worker be documented? What is the objective of engaging casual workers? Do you know that issuing appointment orders, assessing performance, giving salary increments based on performance etc would make the casual workers entitled to regularisation? When a casual employee is engaged following the HR procedures, he can claim regularisation whereas if he is not engaged following the general recruitment formalities, then he can never demand regularisation. Then why should you document his engagement or rather employment?