RE: set-face-attribute and floating point :height values

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

> > It might help if the doc either avoided the undefined term 
> > "underlying face" or explained what it means by that.
> 
> I think the use of the term 'underlying face' is a nice and 
> compact way of describing that floating point :height values
> are multipliers for any :height inherited from another face.
> But it's confusing that there is an exception for the
> 'default' face that makes this particular format of
> :height value invalid for just this *one* exception.
> 
> Maybe we should fix the doc string to mention this exception and
> explicitly mention 'inheritance' instead of the 'underlying face'.

If you look at the doc I pointed to (node `Face Attributes'),
you will see that "underlying face" is not the same as
inherited face.  According to what is written, underlying is
not about inheritance.  (I don't claim that what is written is
correct.)

An underlying face is "a face that has a lower priority in
the list described in `Displaying Faces'".  In `Displaying
Faces' you will see the ways in which the list of faces that
underly a given face can be constituted.  And you will
notice that there is no mention of inheritance.

In node `Face Attributes', face inheritance is also discussed,
however (see `:inherit').  It is explicitly distinguished from
underlying: "Attributes from inherited faces are merged
into the face like an underlying face would be, with
higher priority than underlying faces (`Displaying Faces')."