Path: "Indicators" -> "Optional strikes"
Open Interest (OI) - shows the number of opened option contracts for each strike. Large OI indicates the interest of market participants in the price level.
OI increase (Days) - is highlighted in dark color at the ends of the strikes. Shows adding of OI for each strike for a user-specified number of days.
Strikes lightning - highlighting the strike on which the volume passed (within 1 minute) and when you double-click on a particulare trade.
Volumes on chart - displays all Put/Call volumes that are greater than the "Min. total volume" (except block trades).
When you double-click on the triangle with the corresponding direction (down - trades made by Bid, up - through the Ask side), information pops up, what volume was passed, at what strike and who initiated the deal.
Transeparency indicates how large this volume is, in relation to the base value specified by the user. The more filling - more volume. Strikes are highlighted with a signal color.
Volume - shows the volumes traded for each strike for the current day from midnight Chicago time.
Min. total volume - the number of contracts above which traded volumes are displayed on the chart.
Block trades (BT) are targeted transactions that take place between participants outside the order book. The registration time for a block trade on the exchange is up to 15 minutes. They are indicated on the graph as squares and do not contain information about the initiator. Key "4" - removes BT from the chart.
Central strikes - the upper and lower strikes in relation to the price of the underlying asset at the moment.
If the price exactly matches the strike price, then the volumes will be displayed for one central strike.
Strikes info - activates information about the volume that has passed during the day on Call and Put options (above from the strike) and open interest accumulated on the strike since the beginning of the contract (below from the strike). Also, this information is displayed in the lower right corner when you put the crosshair position over the option strike.
Alert (bells) - sends a notification to the platform and to the mail about new volumes. You can choose central strikes, in-the-money strikes, block trades, all together or individually.
In-the-money strikes - option trades on "in-the-money" strikes are highlighted with a bold border. The further away from the current price (deeper into the money) the more intrinsic value it has.
These options are bought in large volumes, often by market participants who are more aware of future price movements, as they are much more expensive than out-of-the-money or center strike options.
But you need to watch the addition of OI at the strike the next day, to see exactly whether new positions were opened or old ones were closed.