VIPIN SANGHI, J.

1. The petitioners have preferred this writ petition to assail the order dated 27.09.2018 passed by the Central Administrative Tribunal, Principal Bench, New Delhi (‘Tribunal’) in OA No.4247/2017. The said Original Application preferred by the petitioners had been rejected by the Tribunal by the impugned order.

2. Petitioner No.1 to 4 are Trade Unions of employees of the respondent-National Projects Construction Corporation Limited (‘NPCC’). Petitioner No.5 is one of the employees of the respondent-NPCC and he is a member of the petitioner No.1-Bihar RPNN Ltd. Employees Union.

3. The petitioners earlier preferred Civil Writ Petition No.1052/2001 before this Court, which was transferred to the Tribunal and renumbered as OA No.4247/2017. The petitioners, in the said petition, sought a direction in the nature of Certiorari to quash the office order No.500137/IDA dated 29.05.1998. By the said office order, the respondent considered the issue of revision of IDA pay-scales and allowances in respect of the employees, who were below Board level Executives, Staff Members in NPCC w.e.f. 01.01.1992. Para 2.3 of the said order specifically excluded, from the said revisi