organic chemistry - What does the "h" "k" and "(5.2.2.02,6)" mean in Dibenzo(h,k)-4-oxatricyclo(5.2.2.02,6)undec-8,10- diene-3, 5-dione

I am preparing to do an experiment that involves synthesizing Dibenzo(h,k)-4-oxatricyclo(5.2.2.0^2,6)undec-8,10- diene-3, 5-dione via a Diels-Alder reaction.

Could someone please explain the nomenclature for this molecule? Specifically, what the "h", "k" and (5.2.2.0^2,6) mean?

Below is the reaction:

Answer

The systematic (but not necessarily preferred) name tricyclo[5.2.2.0^2,6]undecane describes the structure of octahydro-1⁠H-4,7-ethanoindene (see this answer on how to name tricyclo compounds):

Expanding the name from tricyclo[5.2.2.0^2,6]undecane to 4-oxatricyclo[5.2.2.0^2,6]undec-8,10-diene-3,5-dione adds the functional groups, which leads to the structure of 3a,4,7,7a-tetrahydro-4,7-etheno-2-benzofuran-1,3-dione:

According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), isomers of fused polycyclic ring systems are distinguished by lettering each peripheral side of the parent component using the italic letters a, b, c, etc., beginning with a for the side numbered ‘1,2’, b for ‘2,3’, etc.
For example:

        

Accordingly, fusion of two benzene rings to the above-mentioned parent structure 4-oxatricyclo[5.2.2.0^2,6]undec-8,10-diene-3,5-dione at the relevant sides yields the name dibenzo[h,k]-4-oxatricyclo[5.2.2.0^2,6]undec-8,10-diene-3,5-dione.
(Note that this name does not necessarily correspond to the preferred IUPAC nomenclature and notation.)