40. Perpetually offering to exchange or to sacrifice is a draw.
(See examples in Diagram 101 through 104)

Diagram 101: Red (in Capital) moves first
R8+1 r1+3

R8-3 r1-2

R8+2 r1-3

R8+3 r1+2

R8-2 ....

Explanation:
Red keeps trying to exchange or sacrifice the Rook. Since the Black
Rook is free to move, Red does not violate the rule and this game can
be a draw.

Diagram 102: Red (in Capital) moves first
R73 r67

R32 r78

R24 r86

R41 r69

R12 r98

....

.

.

Diagram 103: Red (in Capital) moves first
R8-3 r4-1

R8+1 r4-2

R8+2 r4-3

R8-3 ....

Explanation:
In Diagrams 102 and 103 neither side violates the rule and the games
can be ruled as draws.

Diagram 104: Red (in Capital) moves first
P78 r23

P87 r32

P78 r23

P87 r32

P78 ....

Explanation:
The Black Rook perpetually threatens to checkmate and the Red Pawn
perpetually tries to sacrifice. Neither side violates the rule
and the game is a draw.

Appendix: Example of Perpetual Chase
P76 m1+3

P67 m3-1

P78 m5+3

P87 m3-5

P76 ....

Explanation:
Red keeps moving its Pawn to keep the Black Knight "unprotected".
This constitutes the Red Rook perpetually chasing the unprotected
Black Knight. Red is violating the rule.

Example of Non-Perpetual Chase
R2+1 c8+1

R2-1 c8-1

R2+1 c8+1

R2-1 c8-1

R2+1 ....

Explanation:
Each of Red Rook's move is threatening the Black Cannon but the
Black Cannon does not try to escape or seek for protection.
This is not a perpetual chase and does not violate the rule.

Example of Mutual Perpetual Chase
R4-2 g4+5

R4+2 g5-4

R6-4 g4+5

R6+4 g5-4

R4-2 g4+5

R4+2 g5-4

R6-4 g4+5

....

Explanation
Red's R4-2 is to allow the Rook on the 6th file to chase
the Black's Cannon on the 9th file. In the next move, R4+2, Red
is using the Rook on the 4th file to chase the Black Cannon on the
9th file. This is two pieces perpetually chasing a piece.
As to the Black side, each time it moves the Guard it is threatening
the Red Rook on the 6th file with a Cannon. This is a perpetual chase.

Since both sides violate the rule, the game will be a draw if neither
side wants to change its move.