Universal dataclass replacing *Series

• group_id -- generalized replacement of event_id

• extendible: e.g. add pos, dir to hits

• independent Event (tracks, hits, reco) vs timeslices

• H5: table-based (like mctracks) vs multiple-array (like /hits/tot)

  • h5loc
  • event_info and timeslice_info metadata tables

• Iteration capabilities still possible (covered by recarray)

hits.time -> array
for hit in hits:
    hit.time -> scalar

(dict-like lookup is a bonus)