RE: [External] : Re: Text scale mode and additional fonts

[Drew Adams]

> > (set-fontset-font t 'arabic +bidi-arabic-font)
> >
> > this makes the initial situation better but now the Urdu text is not
> > affected by the `text-scale-mode` commands.
> 
> That's because the :size attribute is absolute: 28.  Instead, use a
> relative value, a float such as 1.5, then it should scale with the
> rest of the text.

Very useful info.  But I don't see that spelled
out clearly in the doc.  There I find only
statements such as these.  Do they perhaps imply
what you stated? 

`:size'

VALUE must be a non-negative integer or a floating point number
specifying the font size.  It specifies the font size in pixels (if
VALUE is an integer), or in points (if VALUE is a float).
___

':size'
  The font size-either a non-negative integer that specifies the
  pixel size, or a floating-point number that specifies the
  point size.
___

Is such info already documented somewhere?
If not, should it be?  An explicit statement
about point-size being scalable might help.