List choices as alias? and dependencies?

I’m working on a 3D scatter plot app in Python. I need to have drop down menus in a linked spreadsheet. The dropdown menu needs to populate the cell with letter/phrase that Python will recognize. Specifically marker types (< ^ > v x o , , + X D h p s) and colors (r g b k c m y tab:otange tab:purple and gold) 10 options each. I need a drop down menu to simply provide a simple description?)

these two choices are columns E & F

I input for both E & F IF required in there is an an entry in A AND B AND C

Can this be done?

Thank you!!