A.18.1 The Package Containers
The package Containers is the root of the containers 
subsystem. 
Static Semantics
The library package 
Containers has the following declaration: 
package Ada.Containers 
is
   pragma Pure(Containers);
 
   type Hash_Type 
is mod implementation-defined;
 
   type Count_Type 
is range 0 .. 
implementation-defined;
 
   Capacity_Error : 
exception;
 
end Ada.Containers;
Hash_Type represents the range of the result of a 
hash function. Count_Type represents the (potential or actual) number 
of elements of a container. 
  Capacity_Error is raised when the capacity of a 
container is exceeded.
Implementation Advice
Hash_Type'Modulus should be at least 2**32. Count_Type'Last 
should be at least 2**31–1. 
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe