Authority
to proceed
means the authority given to the LP of a train, under the system of working, to
enter the block section with his train;
Block
Back
means to dispatch a message from a block station intimating to the block
station immediately in rear on a double line, or to the next block station on
either side on a single line, that the block section is obstructed or is to be
obstructed;
Block
Forward
means to dispatch a message from a block station on a double line intimating to
the block station immediately in advance
the fact that the block section is obstructed or is to be obstructed;
Block
section
means that portion of the running line between two block stations on to which
no running train may enter until Line Clear has been received from the block
station at the other end of the block section;
