Strong resonant enhancements of the charge-order and spin-order superstructure-diffraction intensities in La1:8Sr0:2NiO4 are observed when x-ray energies in the vicinity of the Ni L2;3 absorption edges are used. The pronounced photon-energy and polarization dependences of these diffraction intensities allow for a critical determination of the local symmetry of the ordered spin and charge carriers. We found that not only the antiferromagnetic order but also the charge-order superstructure resides within the NiO2 layers; the holes are mainly located on in-plane oxygens surrounding a Ni2+ site with the spins coupled antiparallel in close analogy to Zhang-Rice singlets in the cuprates.