Trade "a special" for "special case" later

Based on comment by Hans:
- modelica#2916 (comment)

chapters/inheritance.tex

@@ -577,7 +577,7 @@ \section{Redeclaration}\label{redeclaration}
 A \lstinline!redeclare! construct as an element replaces the declaration of a local class or component with another declaration.
 Both \lstinline!redeclare! constructs work in the same way.
 The \lstinline!redeclare! construct as an element requires that the element is inherited, and cannot be combined with a modifier of the same element in the extends-clause.
-For modifiers, the redeclare of classes uses a special \lstinline[language=grammar]!short-class-definition! construct, which is a subset of normal class definitions and semantically behaves as the corresponding \lstinline[language=grammar]!class-definition!.
+For modifiers, the redeclare of classes uses the \lstinline[language=grammar]!short-class-definition! construct, which is a special case of normal class definitions and semantically behaves as the corresponding \lstinline[language=grammar]!class-definition!.
 
 A modifier with the keyword \lstinline!replaceable!\indexinline{replaceable} is automatically seen as being a \lstinline!redeclare!.