We intend to have a discussion on extensions of the Les Houches event file format, gearing towards an update which merges proposed and de facto in use extensions of the standard in a coherent way.

(L. Lönnblad, S. Plätzer + A. Buckley + …)

More material on extension for reweighting is here

Some extra concerns:

• Support for weight matrixes to correlate multiple simultaneous scale/PDF variations (Maria Vittoria Garzelli)
• Identification of meaning of weights, esp for experiment use where the users know little about how the generator was run (Andy Buckley)

Extension for the mundane but important issue of being able to track the generator(s) name and version(s) responsible for the LHE file, and to add the same information to HepMC is also needed, particularly for event provenance in the experiments. This can probably be achieved by adding a list of pairs of (genname, genversion) strings to each format.