> ## Documentation Index
> Fetch the complete documentation index at: https://docs.commonality.co/llms.txt
> Use this file to discover all available pages before exploring further.

# Selectors

Selectors are used apply checks constraints and constraints to subsets of packages in a project and are defined in a [project configuration file](/reference/project-configuration).

## Select all packages

Use the `*` selector to apply constraints and checks to all packages.

**Example check:**

```json .commonality/config.json theme={null}
{
  "checks": {
    '*': [recommended.hasReadme()],
  }
}
```

**Example constraint:**

```json .commonality/config.json theme={null}
{
  "constraints": {
    "*": { "disallow": ["deployable"] }
  }
}
```

## Select packages with a tag

Select a tag to apply constraints and checks to a subset of packages.

**Example check:**

```json .commonality/config.json theme={null}
{
  "checks": {
    "buildable": ["has-build-scripts"]
  }
}
```

**Example constraint:**

```json .commonality/config.json theme={null}
{
  "constraints": {
    "config": { "disallow": ["application"] }
  }
}
```