# Advanced Strategies \[Non-custodial execution with an on-chain policy engine and standardized NAV]

:::info
In Railnet smart contracts, an Advanced Strategy is implemented as a **Specialized Vehicle**.
:::

An Advanced Strategy runs your own execution logic against any contract — lending, borrowing, swaps, bridges, perpetual futures, RWA operations — while standardizing the three things usually left to bespoke setups: custody, policy enforcement and valuation.

<AdvancedOverview />

## Custody

Capital sits in a Safe deployed per strategy, with the policy engine enabled as a module. It is genuinely non-custodial: no workspace owner, infrastructure provider or third party holds a key that can recover it, and the admin quorum cannot execute asset management operations on its own. The asset manager brings their own signers, quorum and automation; the contracts either accept an operation or reject it. The same Safe address is deployed deterministically on every supported chain, so cross-chain strategies share one identity.

## Policy

A **Zodiac Roles Modifier v2** instance governs what the asset manager may do: which contracts can be called, which functions on them, and which parameter values are accepted, plus spending limits that refill on a period. Policy changes pass through a guardian timelock. Every rule is on-chain, so platforms and depositors can read the exact constraints on a strategy before allocating. See [Policy engine](/strategies/advanced/policy-engine).

## Valuation

An ERC-7540 vault is the capital entry point. It handles subscriptions, redemptions, share pricing, fees and access control, and settles pending requests against a NAV proposed by a valuation manager and confirmed by the Strategy. NAV guardrails bound how far the price per share can move in one update. The valuation format is the same across every Advanced Strategy, which lets platforms and risk teams compare them directly. See [Vault 7540 mechanics](/strategies/advanced/vault) and [Accounting](/strategies/advanced/accounting).

## How it connects

Railnet's generic [`ERC7540Vehicle`](/yield-sources/erc-7540) adapter wraps the vault in full-async mode, so every deposit and redeem goes through the vault's request queue and the vault's sync paths must stay disabled. There is no Lagoon-specific adapter: to Railnet, an Advanced Strategy is one more ERC-7540 yield source. That makes it distributable through a [Conduit](/conduits) with your own fees and compliance rules, and holdable as a sub-vehicle inside an [Allocation Strategy](/strategies/allocation) alongside standard Vehicles, with sector accounting tracking its NAV like any other source.

## Next steps

<Cards>
  <Card title="Policy engine" description="Contract whitelists, calldata checks, spending limits, cross-chain scoping." icon="shield-half" to="/strategies/advanced/policy-engine" />

  <Card title="Vault 7540 mechanics" description="Deposits, redemptions, settlement, fees, access control." icon="vault" to="/strategies/advanced/vault" />

  <Card title="Operate an Advanced Strategy" description="Route protocol calls through the policy engine." icon="terminal" to="/strategies/advanced/operate" />
</Cards>