Question: What's the meaning of "csgn(z)" in a function, integral

Hello, I bring here a problem with maple where I make a definite integral and appear suddenly in the solution a "csgn".

Here is the integral :

(1)

V(z) = (int(int(theta*R*(H-p)/(H*(L*L)*sqrt((R*(H-p)/H)^2+(z-p)^2)), p = 0 .. z), o = 0 .. 2*Pi))/(4*Pi*epsilon)

But i want the solution for z where 0

(2)

V := proc (z) options operator, arrow; (1/4)*(int(int(theta*R*(H-p)/(H*L*L*sqrt(R^2*(H-p)^2/H^2+(z-p)^2)), p = 0 .. z), o = 0 .. 2*Pi))/(Pi*epsilon) end proc

(3)  fsolve(diff(V(z), z) = 0, z)

and the result is 0.75601

Now my question it's about the first ecuation, because I write the code like in (1) to see the solution and this "csgn(z)" freak me out, so I asking does this csgn change my result where 0

Why did it appear, it's because Maple doesn't know the values of z?

I hope someone can help me,

Greetings

PS: English it is not my mother language so I apologize, if wrote wrong some words