Two components of the boundary of \(\text \textbf{I}_3\). (Deux composantes du bord de \(\text \textbf{I}_3\)) The \(b\)-function and the holonomy diagram of a regular simple prehomogeneous vector space (\(\text{GL}(1)^2 \times\text{Spin} (10)\), half-spin rep. + vector rep.) 