1. There are two phosphorus centers, each bearing a double-bonded oxygen (=O) and two methoxy (-OCH3) groups.
2. Call the phosphorus attached to a single ring "Phosphorus A." Phosphorus A is bonded to:
   - Two -OCH3 groups
   - A six-membered ring (Ring A) composed of five carbons and one oxygen, with all single bonds. Label the ring atoms A1 through A6 so that A1 is the carbon directly attached to Phosphorus A, then proceed around to A6 and back to A1. A4 is the oxygen.
3. At atom A1 of Ring A, there is an alkylene-diamine linkage leading to another ring:
   -N-CH2-CH2-N- connecting to a second six-membered ring (Ring B).
4. Ring B, with five carbons and one oxygen, is labeled B1 through B6. B1 is the carbon bonded to the terminal nitrogen of the linker, and B4 is the oxygen. On B1, there is "Phosphorus B," which also has a =O and two -OCH3 substituents. Continue numbering around the ring to B6, returning to B1.
5. No other substituents are present. There is no specified stereochemistry.
