“…For each property what is new, expected, proved, numerically observed, and its context? First, evolving the solution subspaces, considered as curves in the Grassmann manifold is not new for autonomous problems-see Hermann and Martin [44,45,46,47,48], Martin and Hermann [71] Brockett and Byrnes [18], Shayman [92], Rosenthal [87], Ravi, Rosenthal and Wang [86], Zelikin [100], Abou-Kandil, Freiling, Ionescu and Jank [1] and Bittanti, Laub and Willems [12]. Using Riccati systems to solve nonautonomous spectral problems is also not new-see Johnson [56], Hutson [51], Pryce [85], Manopoulous and Gray [69], Gray and Manopoulous [38] and Chou and Wyatt [23,24].…”