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

# Targeting

> Rule-based flag evaluation using evaluation context attributes

Targeting rules let you serve specific values to specific users based on attributes you pass at evaluation time. Rules are evaluated in order; the first rule whose conditions all match determines the returned value. If no rule matches, evaluation falls through to the global rollout or the flag's default value.

***

## Rule structure

Each rule consists of:

* **Conditions**: one or more attribute checks that must all pass (AND semantics)
* **Serve**: the value to return when all conditions match

```
IF  country equals "Nigeria"
AND platform equals "ios"
THEN serve "variant-a"
```

You can create as many rules as needed. Rules execute top-to-bottom; the first match wins and evaluation stops.

***

## Conditions

A condition evaluates an attribute from the evaluation context against a configured value using an operator. Attribute names correspond to the fields in `EvaluationContext`, or any custom key-value pair you include.

### Operators

| Operator                | Applies to     | Description                          |
| ----------------------- | -------------- | ------------------------------------ |
| `equals`                | string, number | Exact match                          |
| `not equals`            | string, number | Does not match                       |
| `in list`               | string, number | Value is one of a configured set     |
| `not in list`           | string, number | Value is not in the set              |
| `contains`              | string         | Substring match                      |
| `starts with`           | string         | Prefix match                         |
| `ends with`             | string         | Suffix match                         |
| `greater than`          | number         | Strict numeric comparison            |
| `greater than or equal` | number         |                                      |
| `less than`             | number         |                                      |
| `less than or equal`    | number         |                                      |
| `exists`                | any            | Attribute is present in the context  |
| `does not exist`        | any            | Attribute is absent from the context |

### Multiple conditions (AND)

All conditions in a rule must match. There is no built-in OR within a single rule. To express OR logic, create separate rules.

```
Rule 1: country equals "Nigeria"  AND  platform equals "ios"   → serve "variant-a"
Rule 2: country equals "Ghana"                                 → serve "variant-b"
Rule 3: (no conditions)                                   → serve "control"     ← catch-all
```

A rule with no conditions always matches. Use it as the last rule to define a catch-all when you want explicit control over the fallthrough value rather than relying on the global rollout.

***

## Evaluation context

The evaluation context is the set of attributes you pass when calling a flag hook or method. The SDK makes these available during rule evaluation.

<Tabs>
  <Tab title="React / React Native">
    ```tsx theme={null}
    useFlag('checkout.charge-delivery-fee', {
      customerId:    '4821',
      country:       'Nigeria',
      city:          'Lagos',
      platform:      'ios',
      appVersion:    '4.1.0',
      plan:          'enterprise',   // custom attribute
    });
    ```
  </Tab>

  <Tab title=".NET">
    ```csharp theme={null}
    var ctx = new EvaluationContext
    {
        CustomerId = 4821,
        Country    = "Nigeria",
        City       = "Lagos",
        Platform   = "api",
        AppVersion = "4.1.0",
    };

    ctx["plan"] = "enterprise";   // custom attribute
    ```
  </Tab>
</Tabs>

### Built-in attributes

| Attribute          | Type               | Notes                                                      |
| ------------------ | ------------------ | ---------------------------------------------------------- |
| `customerId`       | `string \| number` | Primary bucketing key for rollout                          |
| `agentId`          | `string \| number` | Secondary bucketing key; used when `customerId` is absent  |
| `businessId`       | `string \| number` | Tertiary bucketing key                                     |
| `businessBranchId` | `string \| number` |                                                            |
| `country`          | `string`           | Full country name (e.g. `"Nigeria"`, `"Ghana"`)            |
| `city`             | `string`           |                                                            |
| `platform`         | `string`           | `web`, `ios`, `android`, `api`, etc.                       |
| `appVersion`       | `string`           | Semver string; supports prefix matching for version ranges |

### Custom attributes

Any key-value pair you include beyond the built-in attributes is passed through to the evaluation engine and can be referenced in targeting rules by name. This lets you target on application-specific properties like subscription plan, account type, or experiment cohort, without changes to the SDK or backend.

***

## Rule ordering

Rules are evaluated top-to-bottom. The **first** rule whose conditions all match wins; subsequent rules are not evaluated. Order rules in the dashboard by dragging them to set priority.

**Example:** A rule that matches a specific customer ID should appear before a broader country-level rule, or it will never be reached if the country rule matches first.

***

## Fallthrough

When no targeting rule matches, evaluation falls through in this order:

1. **Global rollout**: if rollout is configured, the user is deterministically bucketed into the traffic split. The returned reason is `ROLLOUT` (boolean) or `SPLIT` (multi-value).
2. **Default value**: if no rollout is set, the flag's configured default value is returned. The returned reason is `DEFAULT`.

See [Evaluation](/concepts/evaluation) for the complete evaluation algorithm and all reason codes.