cannot understand Elisp manual node Glyphs

["Drew Adams" <drew.adams@oracle.com>]

I can't tell how much of this problem is me and how much is the text, but I
don't understand this Elisp manual node.

I use the following code, to display ^L using a vector of glyphs that says
this:

__________ Section (Printable Page) __________

(defcustom 1on1-^L-appearance-vector
  (vconcat (make-vector 10 ?_)
           " Section (Printable Page) "
           (make-vector 10 ?_))
 "..." ...)

(aset standard-display-table ?\014 1on1-^L-appearance-vector)

That works fine. However, I'd like to also apply a face to the displayed
glyphs. I figure that manual node Glyphs is trying to tell me, among other
things, how to do that, but I can't figure it out.

It seems to say that the glyphs that I am using, and should be using, have
"simple glyph codes". It does not say what a glyph "code" is, BTW.

It also says that a simple glyph code specifies both a character and a face.
The character is the code mod 524288; the face number is the code / 524288.

So how do I use that information, to apply a face to my vector of glyphs?
Maybe that's not the right way to say it. How can I have the glyph vector
that I use to display ^L appear in a particular face?

There seems to be a wide gulf between the kind of info that is available in
this node (glyph codes, face numbers) and practical use of that information.
I imagine that I'm not too far from my quest, but I haven't a clue where to
head.

Assistance appreciated. Perhaps we can improve the manual a bit in the
process.