# XO1315: `edition 2026` is the old name of `edition preview`

Before 1.0 the only edition is `preview` (decision 0155): nothing is frozen in the 0.x releases, and the compatibility promise of core 13 starts with the first frozen edition, which is named at 1.0. Modules written before the rename say `edition 2026`. That name stays an alias of `preview` during the 0.x releases, so they keep building, and `xo check` reports this note on the `edition` line of xo.mod. The note carries a fix that rewrites the line; `xo fix` (or `xo check --fix`) applies it.

## Example

```xo
// xo.mod
module example.com/api
edition 2026
```

## Fix

```xo
// xo.mod
module example.com/api
edition preview
```

Run `xo explain XO1315` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).