Declarations introduce new entities that denote types, variables, attributes, and packages. Some declarations can only appear immediately within a project declaration. Others can appear within a project or within a package.
declarative_item ::= simple_declarative_item | typed_string_declaration | package_declaration simple_declarative_item ::= variable_declaration | typed_variable_declaration | attribute_declaration | case_construction | empty_declaration empty_declaration ::= *null* ;
An empty declaration is allowed anywhere a declaration is allowed. It has no effect.