Section 2(1)(m) in The Competition Commission of India (General) Regulations, 2009
(m)"working day" for the office of the Commission at New Delhi or any other office of the Commission means the day on which it functions but does not include Saturday or Sunday or any other day which is declared to be a public holiday by the Central Government under the Negotiable Instruments Act, 1881 (26 of 1881) for New Delhi or for such other place, as the case may be.