J.7 At Clauses

Reason: The preferred syntax for specifying the address of an entity is an attribute_definition_clause specifying the Address attribute. Therefore, the special-purpose at_clause syntax is now obsolete.

The above equivalence implies, for example, that only one at_clause is allowed for a given entity. Similarly, it is illegal to give both an at_clause and an attribute_definition_clause specifying the Address attribute. 

We now allow to define the address of an entity using an attribute_definition_clause. This is because Ada 83's at_clause is so hard to remember: programmers often tend to write “for X'Address use...;”. 

Ada 83's address_clause is now called an at_clause to avoid confusion with the new term “Address clause” (that is, an attribute_definition_clause for the Address attribute).