Shellability of Oriented Matroids

This invention relates to herbicidally active diphenyl ether compounds, herbicidal compositions thereof and the control of weeds therewith, said compounds represented by the formula wherein A is: wherein: X is hydrogen or halogen; Y is hydrogen, halogen, cyano, trifluoromethyl, or alkyl containing up to 4 carbon atoms; Z is nitro, halogen, or cyano; and R and R1 are the same or different and represent hydrogen, halogen, or alkyl containing up to 10 carbon atoms, or R and R1 may join together to form a benzene ring.