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This content applies to WaaS 1.0 only. We highly recommend that you upgrade to WaaS 2.0.
You can add additional data, referred to as hint, during a smart contract call in order to accelerate the validation process and save on gas fees. The hint field can be passed in in a CallData struct as follows when a transaction is sent to an Authorizer: 
struct CallData {
    uint256 flag; // 0x1 delegate call, 0x0 call.
    address to;
    uint256 value;
    bytes data; // calldata
    bytes hint;
    bytes extra; // for future support: signatures etc.
}
With ArgusRootAuthorizer, for instance, multiple Roles can be assigned to a Delegate and each Role can be associated with multiple Authorizers. A transaction will be approved if it successfully passes validation from any of these Authorizers. In this case, Role and Authorizer can be used as hint to determine the specific Authorizer whose validation the transaction will pass:
  1. Execute the execTransaction() function by making an eth_call call without setting the hint field. The hint field returned in TransactionResult will be the hint of this transaction.
  2. Pass in this hint to CallData.
  3. Decode hint in ArgusRootAuthorizer to query the Role and Authorizer.
  4. Use Role Manager to validate whether the Role obtained in step 3 corresponds to the Delegate of this transaction.
  5. Validate whether the Authorizer obtained in step 3 has been registered in ArgusRootAuthorizer.
  6. The hint is considered invalid if either step 4 or step 5 fails. The transaction will be directly rejected.
  7. The hint is considered valid if both step 4 and step 5 succeed. You can use the Authorizer specified in the hint to validate the transaction.
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