Meaningful differences in the rotational intensity structure of oxygen's red atmospheric transition, with respect to widespread expectations, have been recently brought to light by correlating branches linestrengths deduced from an emission experiment [G. Di Stefano, Chem. Phys. 302 (2004) 243]. Given interpretation was that a full (b) case of Hund (with new linestrength functions) takes place in oxygen, instead of forecast (a-b) case, because of a strong rotational uncoupling of spin from molecular axis. Here, the method of linestrength correlation is applied to oxygen's data from absorption experiments, where both absorptions and emissions are present in a dynamic equilibrium. Accordingly, a new technique of discriminating correlations for deduction of intensity structures is applied to data. The reliability of intensity data is also appraised by deduced structures. Considered data, often used in environmental studies, had been obtained with various techniques and under different conditions, and are findable in the literature of last decades. (c) 2006 Elsevier B.V. All rights reserved.