}
	t.nextExtra++
	id := t.nextExtra
	t.extraStrings = append(t.extraStrings, s)
	t.extraStringIDs[s] = id
	return id
}

// getExtraString returns the extra string for the provided ID.
// The ID must have been produced by addExtraString for this evTable.
func (t *evTable) getExtraString(id extraStringID) string {
	if id == 0 {
		return ""
	}
	return t.extraStrings[id-1]
}

// dataTable is a mapping from EIs to Es.