# T302

> type contains itself

**Severity** Error

A record type contains a field of its own type, directly or through other records. Records are stored by value, so such a type would have infinite size.

Break the cycle: store an index or an id that refers to the other record, and keep the records in an array or map.

## Failing example

```flowscope
script "Level chain"
data chart = subscribe(data.ohlcv)
type Level {
  price: float
  next: Level
}
state levels = map<int, float>(100)
on chart.close {
  levels[chart.index] = chart.close ?? 0.0
}
```

## Fixed example

```flowscope
script "Level chain"
data chart = subscribe(data.ohlcv)
type Level {
  price: float
  nextIndex: int
}
state levels = map<int, float>(100)
on chart.close {
  levels[chart.index] = chart.close ?? 0.0
}
```

## Related

- [L001](/docs/scripting/reference/diagnostics/l001)
- [T301](/docs/scripting/reference/diagnostics/t301)