Thank you for your answer and advise. The "problem" for me is this step:
I do not really need Maple to come up with this solution. Therefore, I thought, it could be done more by itself without giving this piece of explicit information.
Furthermore, the ultimate goal is to solve a system of PDEs (two coupled transport equations, one is damped):
sys1 := [diff(p(x,t),x) + 1/A*diff(mdot(x,t),t) + d*mdot(x,t) = 0, diff(mdot(x,t),x) + A/RL/T*diff(p(x,t),t) = 0];
sol1 := pdsolve(sys1);
The solution contains the constants(?) _C1, _C2, _C3 and _c. If these are not constants but functions then the argument is missing. I do not know how to incorporate my ICs and BCs here. It works, if undamped equations are used:
sys2 := [diff(p(x,t),x) + 1/A*diff(mdot(x,t),t) = 0, diff(mdot(x,t),x) + A/RL/T*diff(p(x,t),t) = 0];
sol2 := pdsolve(sys2);