> ## Documentation Index
> Fetch the complete documentation index at: https://base-a060aa97-fix-get-started-governance-approval.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Constants & Addresses

> Copy B20 precompile addresses, roles, policy scopes, variant bytes, policy IDs, and supply-cap constants.

Use `StdPrecompiles.sol` and `B20Constants.sol` from `base-std` as the canonical Solidity source. This page lists the same values for quick reference.

## Precompile Addresses

These addresses are identical on every network where B20 is active.

| Surface | Address |
| - | - |
| B20 Factory | `0xB20f000000000000000000000000000000000000` |
| ActivationRegistry | `0x8453000000000000000000000000000000000001` |
| PolicyRegistry | `0x8453000000000000000000000000000000000002` |

## Roles

| Role | Solidity constant |
| - | - |
| Default admin | `bytes32(0)` |
| Mint | `keccak256("MINT_ROLE")` |
| Burn | `keccak256("BURN_ROLE")` |
| Deprecated blocked burn | `keccak256("BURN_BLOCKED_ROLE")` |
| Seize | `keccak256("SEIZE_ROLE")` |
| Pause | `keccak256("PAUSE_ROLE")` |
| Unpause | `keccak256("UNPAUSE_ROLE")` |
| Metadata | `keccak256("METADATA_ROLE")` |
| Asset operator | `keccak256("OPERATOR_ROLE")` |

## Policy Scopes

| Scope | Solidity constant |
| - | - |
| Transfer sender | `keccak256("TRANSFER_SENDER_POLICY")` |
| Transfer receiver | `keccak256("TRANSFER_RECEIVER_POLICY")` |
| Transfer executor | `keccak256("TRANSFER_EXECUTOR_POLICY")` |
| Mint receiver | `keccak256("MINT_RECEIVER_POLICY")` |
| Seize exempt | `keccak256("SEIZE_EXEMPT_POLICY")` |
| Seize receiver | `keccak256("SEIZE_RECEIVER_POLICY")` |

## Policy IDs

| Name | Value |
| - | - |
| `ALWAYS_ALLOW` | `0` |
| `ALWAYS_BLOCK` | `(uint64(uint8(IPolicyRegistry.PolicyType.ALLOWLIST)) << 56) \| 1` |

Custom policy IDs use this layout:

```text Policy ID Layout theme={null}
[8-bit PolicyType][56-bit counter]
```

Policy type bytes:

| PolicyType | Byte |
| - | -: |
| `BLOCKLIST` | `0x00` |
| `ALLOWLIST` | `0x01` |
| `UNION` | `0x02` |
| `INTERSECT` | `0x03` |

## Variant Bytes

| Variant | Byte | Address shape |
| - | -: | - |
| `ASSET` | `0x00` | `0xB200...` |
| `STABLECOIN` | `0x01` | `0xB201...` |

## Supply and Decimals

| Constant | Value | | | |
| - | -: | - | - | - |
| Minimum Asset decimals | `6` | | | |
| Maximum Asset decimals | `18` | | | |
| Maximum supply cap / no-cap sentinel | `type(uint128).max` | | | |
| All features paused bitmask | `15` (\`TRANSFER | MINT | BURN | SEIZE\`) |

## Imports

```solidity Solidity Imports theme={null}
import {StdPrecompiles} from "base-std/StdPrecompiles.sol";
import {B20Constants} from "base-std/lib/B20Constants.sol";
```