These alerts appear any time a stock changes between being up for the day, and being down for the day.  These compare the current price to the price of the open.  Daytraders typically use the open, not the close, to decide if a stock is up or down for the day.

These alerts always compare the price of the last print to the price of the most recent open.  In the pre-market, this refers to the open of the previous trading day.  Otherwise this refers to today's open.

More options related to these alerts are listed below.