Okay, here the scenario. 
1) The attachment ("Output.bmp") is the final output after my coding (Codes.txt). 
So right now, I would need to filter some codes out. 
2) Look at the textfield from "Node selection expression:"
This would be the filter. Right now it is "all". It basically means all nodes will be exported. However, this is not what I want. What I want is only export nodes with ui3. ui3 is nothing but a ID and it represents major intersections. 
3) Right now, once I typed something in the "Node selection expression:" textfield, the system basically return an error. (Error.bmp).
After consulting my leader, it was made known to be that we would be mostly dealing with ui3.
4) Instead of a textfield, you could maybe create a drop down list with 2 options (ui3, All). In this case, if an user selects the option of "ui3", he/she will only get back those nodes with ui3. Similarity, if a user were to select "All", the solution would just be like the current code.
I have attached the relevant files to make u understand more. thanks