Velocity sources (experimental): an inlet can take handler: prescribed_velocity with a source written as expressions in x y z t, the arc-length grid-line fractions xi eta zeta and line lengths L_xi L_eta L_zeta, in a cartesian, curvilinear or normal frame, with constraints scale and bulk_velocity (a number or an expression in t); the same source can set the initial condition (properties.initial_conditions.source), inline or by name from a top-level sources:. A source that reads t is re-evaluated once per step. The expression language moves to src/expression.c and gains cosh, sinh, log, atan2 and floor.