Phosphorus oxide can refer to:
Phosphorus pentoxide (phosphorus(V) oxide, phosphoric anhydride), P2O5 Phosphorus trioxide (phosphorus(III) oxide, phosphorous anhydride), P2O3 Phosphorus tetroxide, Between the commercially important P4O6 and P4O10, several other, less common oxides of phosphorus are known. Specifically, P4O7, P4O9, and P2O6 all bear structures intermediate between the endmembers:Luer, B.; Jansen, M. "Crystal Structure Refinement of Tetraphosphorus Nonaoxide, P4O9" Zeitschrift für Kristallographie 1991, volume 197, pages 247-8.
On observation it will be seen that double bonded oxygen in P4O8 at 1,2 position or 1,3 position are identical and both positions have same steric hindrance. Cycle 12341 and ABCDA are identical.
Gases: Phosphorus monoxide, PO Phosphorus dioxide,
References