The FKMM-invariant in low dimension

In this paper we investigate the problem of the cohomological classification of “Quaternionic” vector bundles in low-dimension ($d⩽3$). We show that there exists a characteristic classes $\kappa$, called the FKMM-invariant, which takes value in the relative equivariant Borel cohomology and completely classifies “Quaternionic” vector bundles in low-dimension. The main subject of the paper concerns a discussion about the surjectivity of $\kappa$.