Technical data for this type of fractal : click here (C01-01).

Here :
fn1() = ident(), fn2() = ident(), fn3 = ident(), fn4 = sinh()
real(p1) = 4, imag(p1) = 4, real(p2) = 1, imag(p2) = 0, real(p3) = 2, imag(p3) = 0

If real(p1) = 6 instead of 4, the shape of the fractal looks like this :