Positions
Positions are the contracts, bought on a financial instrument.
There are short and long positions. OMS API does not allow short positions.
The result is a long position for a specific financial instrument.
For each client, for every financial instrument, there can be only one position (with a given number of shares).
The collection of positions are held in Security Deposit.
Current existing positions of a client are called as open position.
If a client SELLs all of a specific financial instrument, the client will not have a position of that financial instrument in its Security Deposit. Those previous positions will be denoted as closed position.