Representation Clauses for tagged types

[d1c@striper.ssd.ray.com (Courville)]

Help!

I'm trying to define a representation clause for a tagged type
and I can't find any information about specifying where the
"tag" goes.  I wan't to do something like this:

	type example_t is tagged
	record
		x: integer;
	end record;

	for example_t use
	record
		TAG at 0 range 0 .. 3;
		x at 0 range 3 .. 7;
	end record;

Can someone help?  Also, another question concerning this is can
I force the tag to be a certain bit size.  It seems my compilier sets
it to 32 bits, I would like it to be just 3 bits.  Can I just do this
in the rep-spec or do I need to do something like:
	for example_t'tag use 3;

Or can I not change this?

Any help would be greatly appreciated, either through a post to this    
newsgroup or by directly emailing me at:

	d1c@ssd.ray.com

Thanks,

Dan