> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-docs-add-b20-spec.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# IPolicyRegistry.createCompositePolicy

> Generated B20 reference for createCompositePolicy(address,PolicyType,uint64[]).

[Related concept](/base-chain/specs/upgrades/beryl/b20/specification/concepts/policies-and-scopes)

## Signature

```solidity theme={null}
function createCompositePolicy(address admin, PolicyType policyType, uint64[] calldata childPolicyIds) external returns (uint64 newPolicyId);
```

| Field               | Value                                                |
| ------------------- | ---------------------------------------------------- |
| Selector            | `0xc341f3f0`                                         |
| Canonical signature | `createCompositePolicy(address,PolicyType,uint64[])` |

## Description

Creates a new composite policy that combines existing simple policies under a logic
gate.
Dev: Child policies must be simple policies (ALLOWLIST or BLOCKLIST), never another composite.
The child-policy set is capped at 4.
Dev: Reverts with `IncompatiblePolicyType` when `policyType` is not UNION or INTERSECT.
Dev: Reverts with `ZeroAddress` when `admin` is `address(0)`.
Dev: Reverts with `ChildPoliciesOutsideOfRange(2, 4)` when `childPolicyIds.length` is not in `[2, 4]`.
Dev: Reverts with `PolicyNotFound` when any child policy does not exist.
Dev: Reverts with `InvalidChildPolicy` when any child policy is not a simple policy or a built-in policy.
Dev: Panics with arithmetic overflow (Panic 0x11) when the policy counter has reached its maximum value.
Param: admin          Initial admin authorized to update child policies and transfer or renounce
administration.
Param: policyType     UNION or INTERSECT.
Param: childPolicyIds Existing simple policy IDs to combine.
Return: newPolicyId The newly assigned composite policy ID.

## Access control

Permissionless creation, but state-changing registry calls require the feature to be active.

## Policy interaction

This is part of the singleton PolicyRegistry surface used by B20 policy scopes.

## Example

```solidity theme={null}
IPolicyRegistry(target).createCompositePolicy(arg0, arg1, arg2);
```

## Related

* [IPolicyRegistry reference](/base-chain/specs/upgrades/beryl/b20/specification/reference/interfaces/IPolicyRegistry)
* [Constants & addresses](/base-chain/specs/upgrades/beryl/b20/specification/reference/constants-and-addresses)