=277. Home, Distant, and Advance Signals.=—A complete system of signals employed in blocking includes first of all the so-called “home” signal at each extremity of a block, then at a distance of 2000 to 2500 feet back from the home signal is placed the “distant” signal. The latter is thus approached and passed before reaching the home signal. On the other side of the “home” signal at least a maximum train length into a block about to be entered by a moving train is placed the “advance” signal. The distance of the advance signal from the home signal may be 1500 to 2500 feet. As a moving train approaches the end of a block it first meets the distant signal, the purpose of which is to indicate what the engineman may expect to find at the home signal. If the distant signal is in the danger position, he will pass it with caution and place his train under control so as to be able to stop at the home signal. If he finds the distant signal in a safety position, indicating the same position of the home signal, he may approach the latter without reducing speed, confident that the next section is clear and ready for him. The advance signal forms a kind of secondary or supplementary block into which the train, under certain conditions, may enter when the block in which it is found is obstructed, but no train may pass the advance signal unless the entire block is clear except when, under permissive working, the train proceeds with caution, expecting to find the track either obstructed or occupied. This group of three signals—the distant, the home, and the advance—taken in the order in which the moving train finds them, is located at each extremity of the block. Although the home signal is said to control the movement of trains in a block at the entrance to which it is found, as a matter of fact it appears that the advance signal in the final event holds that control.