How is TBQ and TSQ computed?

does anyone know what TBQ(tot buy qty) and TSQ(tot sell qty) mean. how is that no. being arrived at?

also, i have noticed that it remains relatively constant and even decreases with the passage of time(volume traded today can only increase with the passage of time). is it kind of, like making "adjustments"- a lot like how the open interest behaves

also, TBQ+TSQ is not equal to total volume traded at any time during the day or even after the markets have closed. in fact there is a very huge disparity all the time.

how are TBQ and TSQ related to volume

TBQ is sum of all the open buy quantity on that scrip on the exchange. Similarly TSQ is the selling quantity. Overall this number may not really change drastically during the day.

This is the total open quantity, that means people who have placed orders to buy/sell and not what has traded.