# Format changelog

> The revisions of the .well format, each linking to its "Changes in v2.x" section in the specification overview.

The format's changelog is part of the specification: each revision adds a "Changes in v2.x" section to the [overview](/format/spec/v2/overview). This page lists the revisions and links to those sections, so there is one record of what changed. Package releases have their own changelogs ([core](/core/changelog), [utils](/utils/changelog), [render](/render/changelog)).

| Revision | `version` written | Shipped in            | Changes                                                     |
| -------- | ----------------- | --------------------- | ----------------------------------------------------------- |
| 2.4      | `"2.4"`           | `@welldot/core` 0.5.0 | [Changes in v2.4](/format/spec/v2/overview#changes-in-v24)  |
| 2.3      | `2`               | `@welldot/core` 0.4.0 | [Changes in v2.3](/format/spec/v2/overview#changes-in-v23)  |
| 2.1      | `2`               | `@welldot/core` 0.3.0 | [Changes in v2.1](/format/spec/v2/overview#changes-in-v21)  |
| 2.0      | `2`               | `@welldot/core` 0.2.0 | [Changes from v1](/format/spec/v2/overview#changes-from-v1) |
| 1        | `1`               |                       | [v1 specification (archived)](/format/spec/v1/well-format)  |

## In brief

- **2.4** writes the version as the string `"M.m"` and adds the site time zone, data logger series, offline `.wellz` packages and vendor-named extensions, plus clarifications. Readers older than `@welldot/core` 0.5.0 reject `"2.4"` files. No deprecations ([details](/format/spec/v2/overview#changes-in-v24)).
- **2.3** adds the operational blocks (attachments, pumps, permits, meters, production, operating regime) and water quality samples, with recommended vocabularies for most open fields. No deprecations ([details](/format/spec/v2/overview#changes-in-v23)).
- **2.1** adds `well_purpose` and `centralizers`, and deprecates `well_type: "artesian"` ([details](/format/spec/v2/overview#changes-in-v21), [deprecations](/format/spec/v2/overview#deprecations-1)).
- **2.0** adds `location`, `well_id`, profiles, the texture object, hydrodynamic events, aquifer analysis, history logs and precision fields, and fixes all units to SI ([details](/format/spec/v2/overview#changes-from-v1)).

Within version 2, every revision is additive: a valid file from an earlier revision stays valid ([deprecation policy](/format/spec/v2/format-reference#deprecation-policy)). [Versions and deprecation](/format/concepts/versions-and-deprecation) explains how readers handle them.