Two-way I/O implementation using OpenGL

I searched the internet. There are many examples, but I found that all of them are input in; Output out;

Then assign IO = (OE )? Out: 1 'bz;
I cannot understand it. When the IO direction is output, the out value should be output. For this Io module, the out value should be input.

In should be ouput.

I tried to write a code segment.

ModuleIopin (iopin, in_data, out_data, OE );InoutIopin;OutputIn_data;InputOut_data;InputOE;AssignIn_data =Iopin;AssignIopin = (OE )? Out_data:1'BZ;Endmodule
 

After compilation, the RTL viewer displays the following information, which meets the expected requirements. If you are free, continue the study.

Two-way I/O implementation using OpenGL