Technical data for this type of fractal : click here (C07-010).

For the fractal here :
fn1() = ident(), fn2() = tanh(), fn3() = tanh(), fn4() = tanh().

real(p1) = 3, imag(p1) = 8, real(p2) = 8, imag(p2) = 2, real(p3) = 1, imag(p3) = 1

If imag(p1) = 128 instead of 8, the shape of the fractal is very different :