in the general explanation of MCPs, it is stated that MCP models can solve problems where

F(z) ⟂ z.lo ≤ z ≤ z.up

Meaning that one of three conditions can hold

F(z) > 0 while z.lo = z

F(z) = 0 while z.lo ≤ z ≤ z.up

F(z) < 0 while z = z.up

https://www.gams.com/latest/docs/UG_Mod ... Models_MCP

However, in all examples below on how to implement MCPs, the variable z seems to be reduced to a variable with only an upper bound

**OR**a lower bound. In that case, the code goes something like

z.lo = 3;

...

eq_1 .. F(z) =g= 0;

...

model example eq_1.z ;

I don't see a statement anywhere that tells me how to implement a model where F(z) can be both ≤0 and ≥0, depending on the bound that z reaches. Moreover, I'm told in Table 2 that double bound variables can only be matched with =N= equations, and I don't think that's what I want (I want F(Z) to be equal to zero in all cases where z is between its bounds, so an inequality sign seems wrong to me).

I wasn't able to find an example for code written for an MCP, where a Variable has an upper and a lower bound, resulting in three possible stages.

Thank you in advance for your answers!