[amibroker] Exploration Signal Value Compared to Current Value

[Pete]

I spent over an hour trying to figure this out and failed. It seems to
me the tools available in AFL should provide a solution but I could
not figure it out.
All I want is to create a column in my exploration that would compare
today's close to the close on the date the signal was created.
For instance:
Filter = Cross(C, MA(C,10));
AddColunn( <<Close at Cross>>);
AddColumn( <<Current Close>>);
//And more importantly;
AddColumn(<<[Close at Cross] - [Current Close]>>);

I hope someone out there has a solution.
Thanks,

  Pete  :-)