Title Page

MicrosoftÒ WindowsÔ

Version 3.1

Programmer's Reference Volume 3: Messages, Structures, and Macros

For the Microsoft Windows Operating System

Microsoft Corporation

Information in this document is subject to change without notice and does not represent a commitment on the part of Microsoft Corporation. The software, which includes information contained in any databases, described in this document is furnished under a license agreement or nondisclosure agreement and may be used or copied only in accordance with the terms of that agreement. It is against the law to copy the software except as specifically allowed in the license or nondisclosure agreement. No part of this manual may be reproduced in any form or by any means, electronic or mechanical, including photocopying and recording, for any purpose without the express written permission of Microsoft Corporation.

Ó1987–1992 Microsoft Corporation. All rights reserved. Printed in the United States of America.

ITC Zapf Chancery and ITC Zapf Dingbats fonts. Copyright Ó1991 International Typeface Corporation. All rights reserved.

Copyright Ó1981 Linotype AG and/or its subsidiaries. All rights reserved. Helvetica, Palatino, New Century Schoolbook, Times, and Times Roman typefont data is the property of Linotype or its licensors.

Arial and Times New Roman fonts. Copyright Ó1991 Monotype Corporation PLC. All rights reserved.

Microsoft, MS, MS-DOS, QuickC, and CodeView are registered trademarks, and Windows and QuickBasic are trademarks of Microsoft Corporation.

U.S. Patent No. 4974159

Adobe and PostScript are registered trademarks of Adobe Systems, Inc.

The Symbol fonts provided with Windows version 3.1 are based on the CG Times font, a product of AGFA Compugraphic Division of Agfa Corporation.

Apple, Macintosh, and TrueType are registered trademarks of Apple Computer, Inc.

PANOSE is a trademark of ElseWare Corporation.

Epson and FX are registered trademarks of Epson America, Inc.

Hewlett-Packard, HP, LaserJet, and PCL are registered trademarks of Hewlett-Packard Company.

IBM is a registered trademark of International Business Machines Corporation.

ITC Zapf Chancery and ITC Zapf Dingbats are registered trademarks of the International Typeface Corporation.

Helvetica, New Century Schoolbook, Palatino, Times, and Times Roman are registered trademarks of Linotype AG and/or its subsidiaries.

Arial and Times New Roman are registered trademarks of the Monotype Corporation PLC.

Okidata is a registered trademark of Oki America, Inc.

Document No. PC28917-0492