Assigning specific atoms in Reactor

Hi.

I just started using reactor for my research.

When I open 'alpha-Hydroxynitrite formation' from the library,

I can see that the letter L contains C,  H, Na, Si, K.  (in the software it shows L [H, C, Na, Si, K];5)

It looks like I can assign specific atoms of my interest at certain place.

Could you let me know how to do this? I tried hard but I couldn't find the function to do so.

 

Thank you for your kind support in advance.

 

You can create an atom list (or not list) in the periodic table of Marvin Sketch.

Thank you very much!

I found it