Testbenches commonly uses delays:
reg clk, reset; initial begin clk=0; forever #50 clk = !clk; end initial begin reset = 1; # 1025 reset = 0; end
Other non-synthesisable constructs found in RTL:
Finite state is all that should matter! In »Kiwi we are finding at compile-time a fixed-point on the amount of state needed.