vorra I will look it up, if on Smolensk forum will bring it, it was abbreviation and a link to it explaining what it is, the navigating system.
if on main avia forum- they closed it up yest! it starts with a sign - "we hope for your understanding etc."
I had it even all saved, like copy, save, wanted to transfer here, the diff. btw TU154M and Yak, and couldn't return to this site, several times. I think becuase of volcano, traffic to this site.