DITA 1.2 suggestion--add format, scope, and type attributes for DITA elements missing them

Add format, scope, and type attributes for DITA elements
that carry an href or other reference attribute, but which
do not have these attributes today.

One question here is whether the image element carry a scope
attribute.  The image element carries an href attribute, but
does not carry type, format, or scope.  The type and format
attributes aren't needed in this case since they are implied
by the image element.  Perhaps scope isn't either, but I wonder
if there are cases where scope=peer or scope=external would make
sense for an image and would determine if the graphic file is
copied to the output directory or not.  (Right now we behave as
though scope=local for image.)