@@ -37,10 +37,13 @@
 /*!
  * @class OFCountedSet OFCountedSet.h ObjFW/OFCountedSet.h
  *
  * @brief An abstract class for a mutable unordered set of objects, counting how
  *	  often it contains an object.
+ *
+ * @note Subclasses must implement @ref countForObject: as well as all methods
+ *	 of @ref OFSet and @ref OFMutableSet that need to be implemented.
  */
 @interface OFCountedSet OF_GENERIC(ObjectType):
     OFMutableSet OF_GENERIC(ObjectType)
 #if !defined(OF_HAVE_GENERICS) && !defined(DOXYGEN)
 # define ObjectType id