Dear Firedrake(rs), I am considering a "standard" FEM problem with the following variables h(chi,tau) and phi(chi,tau) as function of transformed coordinate chi and time tau in chi=[0,L]. In the weak formulation, the point value h(Lp,tau), so the function value at 0<chi=Lp<L as well as, of course, the function h(chi,tau) appear in the space integral of the weak form. In essence, due to a transformed moving boundary this point evaluation arises. I can formulate the detailed (nonlinear) matrix-vector FEM and its time discretisation because after the expansion of h(chi,tau) the coefficients h_j(tau) appear and h(Lp,tau) = h_Np(tau) for j =Np, say, such that the distinction between function and point values disappears. I am struggling to see how I can do this on the weak form level in firedrake. It would work in integral form by using a delta function after introducing h(Lp,tau) as an auxiliary scalar variable but I assume that is not available? What is the FD-tactic here which one can employ? Thank you and best wishes, Onno