Just came across the term order blocks which the person mentioning it stated that it is not order flow. Anyone care to add some color and elaborate this distinction?
An OB are rounded and discrete quantities. OF is a generalized term. Example: Nancy was selling blocks of 200 RTY Futures all day. The market isn't liquid enough for that kind of order flow.
Is this the same as lot size in index futures coming through on the tape? ie, a dramatic increase in order size