We present a detailed NMR study of the expected A and anomalous B Cu l
ines on a single crystal of La2CuO4+delta Our results in conjunction w
ith those of neutron scattering and La NMR lead us to conclude that ox
ygen ordering occurs on a microscopic scale in this compound. The orde
red interstitial oxygen gives rise to a distribution of tilts of the C
uO6 octahedra in the B domains. A sawtooth modulation of the octahedra
l tilt, in which the sign of the tilt changes when the tilt reaches a
maximum value, is deduced. In addition we show that macroscopic phase
separation is inhibited in the tetragonal phase where the CuO6 octahed
ra are not tilted.