The function set_relay() sets the relay of block section BLOCK
to the position POSITION. Legal position values are the symbolic constants
GO_IN preparing the block section for a train to enter and
GO_OUT preparing the block section for a train to leave.
Please note that only the block sections ICOC_LN_2 and OCIC_LN_2 within the turning
loops have a relay. When switching the relay from GO_IN to
GO_OUT while a train is running through the block section, the operation
direction must be switched incidentally.
On successful completion the value SUCCESS is returned, otherwise the
value FAILURE.
int get_relay(int BLOCK);
The function get_relay() returns the relay position currently set
by the last call to the function set_relay() for the specified
block section BLOCK. Please note that only the block sections ICOC_LN_2 and
OCIC_LN_2 within the turning loops have a relay.
On successful completion either GO_IN or GO_OUT is returned,
otherwise the value FAILURE.