PMCS currently has 4 different options for its output format. It can produce D0 PHYS OBJ Chunks. From these, it can produce d0-analyze-style root-typles or thumbnails. However, this option is quite slow. So, PMCS has two other options for people needing faster execution times. PMCS has its own "native" format for root tuple output. This format is also stable against changes in the D0 PHYS OBJ chunks and reco_analyze (especially the reco_analyze rcp's, which change all the time). You can also book and fill histograms within PMCS. INthis case, PMCS just outputs these histograms, without any ntuple output. See the Getting Started section for information on how to produce each kind of output. Documentation on the root tuple variables for the native format can be found here .