13. "One check one idle" and "one check and one threatening to check
and capture" are both ruled as draw. (See examples in Diagram 14, 15,
and 16.)

Diagram 14: Red moves first

R7+1 g5-4
R7-1 g4+5
R7+1 g5-4
R7-1 g4+5
R7+1 ....

Explanation:

Red's R7-1 following its R7+1 is not a check. Although Red can
follow R7-1 with C9+2 g4+5 R7+1 g5-4 R7-3 to capture Black's rook,
the move R7-1 itself is an idle. Therefore, this example is an
"one check one idle". Since "one check one threatening to
checkmate" is a draw, "one check one idle" also should be a draw.

Diagram 15: Red moves first

R8-1 k5-1
R8+1 k5+1
R8-1 k5-1
R8+1 ....

Explanation:

After R8+1 Red intends to C64 to capture the black rook. This
is "one check one threatening to check and capture" and is not
perpetual check or perpetual chase. If neither side wants to
change move, this is a draw.

Diagram 16: Red moves first

R7+4 k4+1
R7-4 k4-1
R7+4 k4+1
R7-4 ....

Explanation:

Red intends to R7=6 after R7-4 so that it can capture n or r.
This example is neither perpetual check nor perpetual chase.
This game should be a draw.