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.