@code{extra-expanded}, or @code{ultra-expanded}.
@item :height
-Font height---either an integer in units of 1/10 point, or a floating
-point number specifying the amount by which to scale the height of any
-underlying face, or a function that is called with one argument (the
-height of the underlying face) and returns the height of the new face.
-If the function is passed an integer argument, it must return an
-integer.
+The height of the font. In the simplest case, this is an integer in
+units of 1/10 point.
+
+The value can also be a floating point number or a function, which
+specifies the height relative to an @dfn{underlying face} (i.e., a
+face that has a lower priority in the list described in
+@ref{Displaying Faces}). If the value is a floating point number,
+that specifies the amount by which to scale the height of the
+underlying face. If the value is a function, that function is called
+with one argument, the height of the underlying face, and returns the
+height of the new face. If the function is passed an integer
+argument, it must return an integer.
The height of the default face must be specified using an integer;
floating point and function values are not allowed.
The name of a face from which to inherit attributes, or a list of face
names. Attributes from inherited faces are merged into the face like
an underlying face would be, with higher priority than underlying
-faces. If a list of faces is used, attributes from faces earlier in
-the list override those from later faces.
+faces (@pxref{Displaying Faces}). If a list of faces is used,
+attributes from faces earlier in the list override those from later
+faces.
@end table
For compatibility with Emacs 20, you can also specify values for two