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The Avail blockchain extends Substrate’s functionality with three custom pallets that provide data availability, cross-chain messaging, and governance capabilities.

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Custom Pallets

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DataControl (dactr)

The DataControl pallet manages application-specific data submissions and dynamic block sizing on Avail. Key Features:
  • Application ID (AppID) management with unique key registration
  • Data availability submissions with hash verification
  • Dynamic block dimension proposals (rows × columns)
  • Fee modifiers for data submission
Primary Use Cases:
  • Register application keys for data availability
  • Submit data blobs to the network
  • Adjust block dimensions based on network conditions
Learn more about DataControl →

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Vector

The Vector pallet implements a cross-chain messaging bridge using zero-knowledge proofs to verify Ethereum beacon chain state. Key Features:
  • Ethereum light client verification using Groth16 and SP1 proofs
  • Cross-chain message execution with storage proofs
  • Sync committee tracking and header verification
  • Fungible token and arbitrary message bridging
Primary Use Cases:
  • Bridge messages from Ethereum to Avail
  • Verify Ethereum state transitions
  • Execute cross-chain token transfers
Learn more about Vector →

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Mandate

The Mandate pallet provides a governance mechanism for executing privileged operations through an approved origin. Key Features:
  • Execute root-level calls from approved origins
  • Bypass normal transaction filters
  • Fee-free execution for governance operations
Primary Use Cases:
  • Governance-approved runtime upgrades
  • Administrative operations
  • Protocol parameter updates
Learn more about Mandate →

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Architecture

All three pallets follow Substrate’s FRAME architecture and integrate with the runtime’s core functionality: 
// Example pallet structure
#[frame_support::pallet]
pub mod pallet {
    use frame_support::pallet_prelude::*;
    use frame_system::pallet_prelude::*;

    #[pallet::config]
    pub trait Config: frame_system::Config {
        type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
        // Additional configuration types
    }

    #[pallet::pallet]
    pub struct Pallet<T>(_);

    #[pallet::storage]
    // Storage items

    #[pallet::call]
    // Extrinsic functions

    #[pallet::event]
    // Events

    #[pallet::error]
    // Errors
}

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Common Patterns

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Storage Items

All pallets use FRAME storage macros for type-safe on-chain storage:
  • StorageValue - Single value storage
  • StorageMap - Key-value mappings
  • ValueQuery - Default query behavior

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Events

Pallets emit events for state changes to enable off-chain indexing and monitoring.

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Weight System

All extrinsics include weight calculations for resource metering and fee computation.

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Development Resources

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