This is probably already well-known, but I want to make sure the rules for setting block boundaries are understood before signaling is attempted.
A block serves two main purposes, to define where the power is applied, and to define where signals define the movement of trains. Block boundaries are usually set in yards and sidings to define where the power may be switched and this allows trains to be parked without fear of movement. Additional block boundaries may be set for other purposes, but the area I want to discuss is bounded by track turn-outs. In a passing siding, the track boundary will be at the ends of the legs that connect the turnout to the main line. Frequently, these diverging tracks are powered ny the turnout motor contacts so that only one leg is powered, depending on the turnout direction.
Effectively, the turnout is part of the block that connects to the In side of the turnout. As shown here, the outbound legs of the turnout are gapped or joined with insulated joiners.
The gaps on the outward tracks establish the block boundaries for the sidings. In the case of a yard ladder, each yard track would be gapped to establish a block for each yard track.
The In side of the turnout may establish a block boundary, but the boundary may be before the turnout input. In as yard, several turnouts may be chained together to create a single block for the turnouts. In signaling block determination, this would indicate that each track would be signaled at the out end. In wiring, this allows each yard track to be powered independently of the others,
Is this obvious? I hope so. Signaling and block detection will rely on blocks being understood.