A requirement for what? Am sorry, this does not have a lot of context.
> at ./SystemLayer/Shell.cs:24 is
> using System.Xml.Linq;
>
> at ./SystemLayer/Makefile:139 is
> System.Xml.Linq
>
> > What error did you get?
Ah, this is probably Visual Studio inserting stuff when it should not,
part of some template. I have removed the references as they are not
used.