"Simon Wright" <simon@pushface.org> wrote in message 
news:lyzhrruww2.fsf@pushface.org...
...
> As Karl Müller <mtb23@gmx.de> hinted, you can use the non-standard GNAT
> implementation-defined attribute 'Enum_Rep[1]. The next page describes
> 'Enum_Val.

It's Standard, just not until Ada 2020. See 
http://www.ada-auth.org/standards/2xrm/html/RM-13-4.html#p10.1.

(Yes, borrowed from GNAT.)

                  Randy.