Is there a way to see if a value is declared as a constant

[ldries46 <bertus.dries@planet.nl>]

I have a set of constants that need a different name each for 
readability. It may not be an array.
For instance:
C1 : constant record_item := .....
C2 : constant record_item := .....
C3 : constant record_item := .....
C4 : constant record_item := .....
C5 : constant record_item := .....

Now in a procedure or a function I have to use one of these constants
for instance:

function X(C : record_item) return record_Item is
    RI : record_item;
begin
    ..
    ..
    RI := C -- This C may only be one of the five constants and not 
another record_item
    ..
    ..
     return RI;
end X;

In what way do I test if C is a constant and not another record Item