Simon Wright wrote:

--The code below gives the following error message (gnat 3.09); is this
--right? The attribute denotes a subprogram, subprogram calls include
--actual parameter parts, ...

Quotation from AARM 6.4 Subprogram Calls

   7   {named association} {positional association} A parameter_association
    is named or positional according to whether or not the formal_
    parameter_selector_name is specified.  Any positional associations shall
    precede any named associations.  Named associations are not allowed if
    the prefix in a subprogram call is an attribute_reference.
        7.a   Ramification:  This means that the formal parameter names used
        in describing predefined attributes are to aid presentation of their
        semantics, but are not intended for use in actual calls.

end quotation.

If you look into RM 13.13.2 you'll find formal parameter names italicized,
which I take as an indication that they cannot be used like other formal
parameters.

Christoph  :^)