The FOs are forward with the infantry (in support role) where they can see the targets and Call For Fire (CFF) upon them. They call the FDC on the radio and transmit a request for fire in the format of CFF. The FDC calculates the CFF and send a deflection and elevation to the gun line. The gun line cranks the specified elevation and deflection on the howitzers, punch the artillery shell followed by the bag (powder). Depending on the CFF, the gunline will fire the round when they are ready or when the FO calls and tells them to fire. The FO spots the round and sends a correction back to the FDC and the process starts all over again until its done.