Idle or Idle
From what I recall of A-320 descent - it is calculated with (increased) idle, as if engine anti-ice is ON all the time - this out of concern by Airbus that they don't want you to have an excess of energy at the bottom of your descent, if they would calculate with minimum idle, and you would need engine anti ice during the descent.
This means that usually you will end up with too little energy at the bottom of your descent and thrust will be added (automatically) if you reach the bottom of the (descent) speed margin.
I gather from the DPO snippet of information, that a new descent profile calculation is invented, where the figures for descent thrust will be more accurate to real world usage of low idle, the margin to cater for excess thrust will not be so large anymore.
In a Boeing, they used to calculate the other way around - real idle as standard, and increased (anti ice) idle below the pilot entered flight level for (expected) anti ice usage.
In the 787 however, VNAV descent now uses slightly more than (real) idle thrust for the whole descent. Now the fanatics on environmental fuel consumption can stay level a bit longer than the VNAV Top of Descent and try to fiddle an idle descent in FLCH.