// only to ExperimentEvent via an EventExperimental event.
	expData map[event.Experiment]*ExperimentalData
}

// addExtraString adds an extra string to the evTable and returns
// a unique ID for the string in the table.
func (t *evTable) addExtraString(s string) extraStringID {
	if s == "" {
		return 0
	}
	if t.extraStringIDs == nil {
		t.extraStringIDs = make(map[string]extraStringID)
	}

			delete(it.tasks, TaskID(ev.Args[0]))
			mappedArgs = timedEventArgs{
				ev.Args[0],
				ev.Args[1],
				uint64(ts.parentID),
				uint64(it.evt.addExtraString(ts.name)),
			}
		} else {
			mappedArgs = timedEventArgs{ev.Args[0], ev.Args[1], uint64(NoTask), uint64(it.evt.addExtraString(""))}
		}
	case oldtrace.EvUserRegion:
		switch ev.Args[1] {
		case 0: // start
			mappedType = go122.EvUserRegionBegin
		case 1: // end

		ev.extra(version.Go122)[0] = uint64(ts.parentID)
		ev.extra(version.Go122)[1] = uint64(evt.addExtraString(ts.name))
		delete(o.activeTasks, id)
	} else {
		// Explicitly clear the task info.
		ev.extra(version.Go122)[0] = uint64(NoTask)
		ev.extra(version.Go122)[1] = uint64(evt.addExtraString(""))
	}
	if err := validateCtx(curCtx, event.UserGoReqs); err != nil {
		return curCtx, false, err
	}