Power of Joint Commissioner to issue directions guides Assessing Officers in pending assessments; directions are binding and not appealable. The Power of the Joint Commissioner under Section 144A allows him, on his own motion, a reference by the Assessing Officer, or an assessee's application, to call for and examine records of pending assessment proceedings and issue binding directions to guide the Assessing Officer. No direction prejudicial to the assessee may be issued without giving an opportunity to be heard, and directions on lines of investigation are not deemed prejudicial. The power applies only to matters pending in assessment or reassessment, and directions under this provision are not appealable.