# Metadata

Metadata lets you add custom data to the platform's entities and is used when creating custom rules and metrics. It can be provided in the API through a key-value structure:

```json
"metadata": {
  "categoria_estabelecimento": "vestuario",
  "regional": "SP01"
}
```

## Requirements

### Keys

* Text only.
* Must have up to 32 characters.
* Allow only lowercase unaccented letters, numbers, and underscore (`_`).
* Example: `categoria_produto`

### Values

* Text only.
* Must have up to 64 characters.
* Allow any unaccented letter, numbers, hyphen (`-`), and underscore (`_`), distinguishing uppercase and lowercase in metric consolidations.
* Example: `P01-Xyz_`

## Limitations

There is a limit on the maximum number of metadata per entity. See [Limits and parameters](/en/limits/#metadata) before planning extensive configurations.