/// @return A name suitable for display as a page title or heading.
/// @custom:example "Bitcoin Mining Yield"
/// @custom:example "Lido Staked Ethereum Yield"
/// @custom:example "Gas Costs"
/// @custom:since 0.1.0
function name() external view returns (string memory);

/// @return Short name of the display units of `shares()`.
/// @custom:example "PH/s"
/// @custom:example "ystETH"
/// @custom:example "kgas"
/// @custom:since 0.1.0
function symbol() external view returns (string memory);

/// @return Decimal offset of `symbol()` vs indivisible units of `shares()`.
/// @custom:example If 1 `symbol()` (e.g. "PH/s") represents
///                 1e15 `shares()` (e.g. H/s)
///                 then `decimals()` should return 15.
/// @custom:example If 1 `symbol()` (e.g. "ystETH") represents
///                 1e18 `shares()` (e.g. wei)
///                 then `decimals()` should return 18.
/// @custom:example If 1 `symbol()` (e.g. "kgas") represents
///                 1e6 `shares()` (e.g. milligas per block)
///                 then `decimals()` should return 6.
/// @custom:since 0.1.0
function decimals() external view returns (uint256);

/// @notice Size of the position tracked by this index.
///         Clients SHOULD NOT assume that this value is constant.
///         Clients SHOULD denominate pool shares in the same denomination
///         as `ISilicaIndex.shares()` (see: `symbol()`, `decimals()`).
/// @custom:example 1e15 H/s.
/// @custom:example `ILido.getPooledEthByShares(1 ether)` stETH wei.
/// @custom:example 1e3 milligas per block
/// @custom:since 0.1.0
function shares() external view returns (uint256);

/// @notice Clients MAY transact in any token which is pegged to
///         `balanceToken()`, as long as the `decimals()` match.
///         Clients SHOULD NOT transact in a token which is not pegged to
///         `balanceToken()`; the resulting financial contract will not
///         make sense.
/// @custom:example 0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599 (WBTC on mainnet)
/// @custom:example 0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84 (stETH on mainnet)
/// @custom:example 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 (WETH on mainnet)
/// @custom:since 0.1.0
function balanceToken() external view returns (address);

/// @notice Clients MAY transact in any token which is pegged to
///         `balanceToken()`, as long as the `decimals()` match.
///         Clients SHOULD NOT transact in a token which is not pegged to
///         `balanceToken()`; the resulting financial contract will not
///         make sense.
/// @custom:example 0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599 (WBTC on mainnet)
/// @custom:example 0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84 (stETH on mainnet)
/// @custom:example 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2 (WETH on mainnet)
/// @custom:since 0.1.0
function balanceToken() external view returns (address);