How can I define a spyglass rule?

[luoyanghero]

For example the follow code, according condition_a, check whether have condition_b.
Is there a rule about this, if not, how can I create it?

always@(posedge clk or negedge condition_a) begin
if(condition_a)begin
data[1:0] <= #`DLY 0;
end
else if(condition_b)begin
data <= #`DLY 1;
end
else begin
data <= #`DLY 2;
end
end