Technical data for this type of fractal : click here.

For the curious fractal here :
fn1 = ident(), fn2 = sinh(), fn3 = ident(), fn4 = ident()
real(p1) = 1, imag(p1) = 64, real(p2) = 0.75, imag(p2) = 0, real(p3) = 1.5, imag(p3) = -1.5

Note : if real(p1) is slightly modified (for example 1.1 instead of 1),
the aspect of the fracttal is drastically changed :