When initiating a new borrowing position, the maximum notional amount you could borrow is called the Max Borrow indicator. When you Create a Position, there will be an indicator with the maximum number of tokens you could either lend or borrow, in any given market.
For Max Borrow, the figure shown is calculated in isolation to Portfolio Margin, and provides an indicative amount by applying a loan-to-value (denoted, "LTV") approach, for time/space calculation considerations.
Currently, Max Borrow associated with an asset is defined as:
Where Liabilities = Present Value of Borrowing Positions, which represents the present value of your Trading Account's liabilities (where liabilities are a negative figure).
Current LTV per asset used for this purpose (to be updated periodically, based on market conditions):