ADuM1401 output drive

Can anyone clarify what ADuM1401 side 1 drive value is? The data sheet tells only Absolute Maximum Ratings:

Average Output Current per Pin -18mA to + 18 mA

There are two ways to read this:

average/pin (3 outputs on this side) is max. 18 mA, total 54 mA OR

max. for each 18 mA in averaged in time.

Then there is a table of max. supply/side but this is much higher and contains dynamic part.

What will happen in time if one is loaded with 20 mA and other two have no load?