Dos6.0

				/***
				*stddef.h - definitions/declarations for common constants, types, variables
				*
				*	Copyright (c) 1985-1990, Microsoft Corporation.  All rights reserved.
				*
				*Purpose:
				*	This file contains definitions and declarations for some commonly
				*	used constants, types, and variables.
				*	[ANSI]
				*
				****/
				
				#if defined(_DLL) && !defined(_MT)
				#error Cannot define _DLL without _MT
				#endif
				
				#ifdef _MT
				#define _FAR_ _far
				#else
				#define _FAR_
				#endif
				
				/* define the NULL pointer value and the offsetof() macro */
				
				#ifndef NULL
				#if (_MSC_VER >= 600)
				#define NULL	((void *)0)
				#elif (defined(M_I86SM) || defined(M_I86MM))
				#define NULL	0
				#else
				#define NULL	0L
				#endif
				#endif
				
				#define offsetof(s,m)	(size_t)&(((s *)0)->m)
				
				
				/* declare reference to errno */
				
				#ifdef	_MT
				extern int _far * _cdecl _far volatile _errno(void);
				#define errno	(*_errno())
				#else
				extern int _near _cdecl volatile errno;
				#endif
				
				
				/* define the implementation dependent size types */
				
				#ifndef _PTRDIFF_T_DEFINED
				typedef int ptrdiff_t;
				#define _PTRDIFF_T_DEFINED
				#endif
				
				#ifndef _SIZE_T_DEFINED
				typedef unsigned int size_t;
				#define _SIZE_T_DEFINED
				#endif
				
				
				#ifdef _MT
				/* define pointer to thread id value */
				
				extern int _far *_threadid;
				#endif