there is rarely direct evidence of action in concert and in such situations, the Commission has to determine whether those involved in such dealings had some form of understanding and were acting in co-operation with each other. In most cases, the existence of an anti-competitive practice or agreement must be inferred from a number of coincidences and indicia, which, taken together, may in the absence of another plausible explanation, constitute evidence of an infringement of the competition rules. In the present case, it is important to look at the conduct of the OPs in other tenders as well to infer the existence of any agreement in relation to the Impugned Tender. Modus of a cartel is not a one-time affair; rather, people who cartelise, pursue their anti-competitive agenda through various means, either simultaneously or one followed by the other. They may meet to decide their agenda for cooperation followed by interactions, telephonic or otherwise, regarding terms and modus of cooperation and, later, monitor each other to ensure compliance of their decision. Thus, there is merit in the DG relying upon the cooperation exhibited by OPs in other tenders also. Therefore, the contention of OP-2 is misconceived and must be rejected.