[R-390] R390A rf slug id help needed

[Phil]

I have been contacted by someone kind enough
to get a slug for me but it has raised a
question in my mind.

The slugs in my set of rf racks have small dots
of paint on the tops.  There is white, red, and
no color.  But looking at what I have, there is
no logic to where the colors are placed within
a single rack.  Sometimes white will be in the
front most coil and sometimes in the center or
rear.  It is the same with red and no color.
Is this correct?  Is there any documentation as
to what goes where?

thanks, Phil