def parse_id(id):
  """Return the (NODEREV, REV, OFFSET) of ID, where ID is of the form
     "NODE_ID.COPY_ID.rREV/OFFSET" and NODEREV is "NODE_ID.COPY_ID.rREV".
  """
  node_id, copy_id, txn_id = id.split('.')
  rev, offset = txn_id[1:].split('/')
  noderev = node_id + '.' + copy_id + '.r' + rev
  return noderev, rev, offset