The class definition file provides a complete description of a class, including its relationship to other classes, its instance data, and the methods that it supports and overrides. An interface definition language (IDL) file for the C language also describes information specific to building C-language binding files.

An IDL specification for a single class in a single .IDL file generally has the sections specified in the sample code illustrated in the following sample code:

//# Include directives

//# Type declarations

//# Constant declarations

//# Exception declarations

//# Interface declaration

interface class-name : parent-class
{
   //# Constant declarations

   //# Type declarations

   //# Exception declarations

   //# Attribute declarations

   //# Method declarations

   //# Implementation statement

   #ifdef __SOMIDL__
   implementation
   {
      //# Modifier statements

      //# Passthru statements

      //# Declarations for instance variables
   };
   #endif   // __SOMIDL__

//# Module declaration
};