is there a script allow me to select only top facing polygon or bottom facing polygon or both

[henry.yu]

Hi

I have a geometry has a lot individual elements

Is there a script or way  I can select only the Top facing or bottom face?

Many thanks

Henry

[denisT.MaxDoctor]

There is a built-in Select by Normal in the Graphite selection tools 

[denisT.MaxDoctor]

If you are looking for a MAX Script solution: Select Faces based on normal? 

This is quite old but still makes sense and works

PS. I'm sure you can find many examples on this subject. This is one of the most popular tasks for learning MAX Script.