Herschel loop

A Herschel loop is a Herschel track with no overall displacement. Herschel loops are, in general, oscillators with a period equal to the length of the loop, or a factor thereof. Herschel loops can be compressed to period 62, and a further four ticks can be squeezed out if the output gliders are suppressed. This statement is only true of Herschel loops containing stable components; loops containing oscillators can be compressed further (see Quetzal).