Given an \(\varvec{A}\) -stable rational approximation to \(\varvec{e}^{\varvec{z}}\) of order \(\varvec{p}\) , numerical procedures are suggested to time integrate abstract, well-posed IBVPs, with time-dependent source term \(\varvec{f}\) and boundary value \(\varvec{g}\) . These procedures exhibit the optimal order \(\varvec{p}\) and can be implemented by using just one single evaluation of \(\varvec{f}\) and \(\varvec{g}\) per step, i.e., no evaluations of the derivatives of data are needed, and are of practical use at least for \(\varvec{p \le 6}\) . The full discretization is also studied and the theoretical results are corroborated by numerical experiments.