Madweight requires as input a set of datacards and an lhco file. A lhco file is a text file collecting basic info on all the events of the sample. It stores info about the type of particles in the event (muon, electron, jet, met) and relative pt, eta, phi, btag, ect. More info about the structure of lhco files can be found at:

• http://madgraph.phys.ucl.ac.be/Manual/lhco.html