# Variables

The following are the most important variables used in the contract:

* `_NOT_ENTERED`: a constant that indicates that the lock is not entered
* `_ENTERED`: a constant that indicates that the lock is entered
* `_NO_ID`: a constant that indicates that there is no position ID
* `_NO_ADDRESS`: a constant that indicates that there is no address
* `_GENERAL_LOCK`: a variable that is used as a lock to prevent reentrancy attacks
* `_IN_EXEC_LOCK`: a variable that is used as a lock to avoid potential race conditions
* `POSITION_ID`: a variable that indicates the position ID currently under execution
* `SPELL`: a variable that indicates the spell currently under execution
* `config`: an instance of `IProtocolConfig` that stores the protocol configuration
* `oracle`: an instance of `ICoreOracle` that stores the address of the oracle contract
* `feeManager`: an instance of `IFeeManager` that stores the address of the fee manager contract
* `nextPositionId`: a variable that stores the next available position ID, starting from 1
* `bankStatus`: a variable that stores the status of the bank, each bit stores a certain bank status, e.g. borrow allowed, repay allowed
* `allBanks`: an array that stores the list of all listed banks
* `banks`: a mapping from token to bank data
* `bTokenInBank`: a mapping from bToken to its existence in bank
* `positions`: a mapping from position ID to position data
* `allowContractCalls`: a boolean variable that determines whether to allow calls from contracts or not
* `whitelistedTokens`: a mapping from token to whitelist status
* `whitelistedSpells`: a mapping from spell to whitelist status
* `whitelistedContracts`: a mapping from user to whitelist status