Bolus calculation on the PING does not deduct IOB from a bolus calculation unless the current BG is below target +/- programmed allowance. So, if you give a correction prior to a meal bolus, the amount of IOB from the correction will show up as IOB when you program your meal bolus . . . and the bolus calculation will be for the food you eat . . . rather than the food and BG.
Note that on the meter remote example pics, the bolus recommendation is the same amount as the calculation for the Carb intake.
In the case that HXFNS initially presented:
Carb 3.50 U
BG +1.00 U
IOB -3.00 U
Total = 4.00 U
It would appear that a portion of the IOB was deducted from the total bolus recommendation for the “correction” portion of the bolus . . . based on a current BG . . . but it would require a look at the bolus history to confirm that assumption.
When you have questions about the way a bolus is calculated it is helpful to call the Customer Service Dept so they can explain the way a bolus is calculated . . . or confirm any need for concern.