// number of logical arguments that isn't length-prefixed, even though the
	// value 3 on the wire indicates length-prefixing. For us, that becomes narg
	// == 4.
	narg := b>>6 + 1
	if typ == EvNone || typ >= EvCount || EventDescriptions[typ].minVersion > p.ver {
		return fmt.Errorf("unknown event type %d", typ)
	}

	switch typ {
	case EvString:
		if flags&skipStrings != 0 {
			// String dictionary entry [ID, length, string].

		mappedArgs = timedEventArgs{uint64(ev.StkID), ^uint64(0), uint64(ev.P), ev.G}
	default:
		return Event{}, fmt.Errorf("unexpected event type %v", ev.Type)
	}

	if oldtrace.EventDescriptions[ev.Type].Stack {
		if stackIDs := go122.Specs()[mappedType].StackIDs; len(stackIDs) > 0 {
			mappedArgs[stackIDs[0]-1] = uint64(ev.StkID)
		}
	}

	m := NoThread