Where can I find the precise official definition of historical data?

Hello everyone, I’m currently trying to develop strategies using historical data. I downloaded BTC/USDT perpetual contract historical data from the official website, but I’m not entirely sure about the definition of several columns.

For example

  1. what exactly does the “count” column refer to? Is it the number of orders? Is it calculated unilaterally or bilaterally
  2. volume = taker_buy_volume + taker_sell_volume, or is volume = 2 * (taker_buy_volume + taker_sell_volume

image

I have a minimum order size of 0.002 on the trading platform, so why is there a value of 0.001 appearing in the volume?

So where can I find the precise official definition of historical data? Thx for any help