[MSDN Library June 1998] Optional Report Message Properties (100%)

MSDN Library Visual Studio 6.0 > Platform SDK > Database and Messaging Services > Messaging API (MAPI) > Guide > MAPI Programming Basics > Messages > About Message Properties

[MSDN Library June 1998] Optional Features of ACM Drivers (28.8649712084247%)

MSDN Library Visual Studio 6.0 > DDK Documentation > Windows 95 Device Driver Kit > Design and Implementation Guide > Audio Compression Manager Drivers > About the Audio Compression Manager

[MSDN Library June 1998] Optional Second Element (Only Used by X.25 SVC) (25.6145929694727%)

MSDN Library Visual Studio 6.0 > Platform SDK > Networking and Distributed Services > Microsoft SNA Server > SNA Device Interface Specification > Reference > Message Formats > Open(LINK)

[MSDN Library June 1998] Optional Printer Interface Driver Functions (23.9282541989664%)

MSDN Library Visual Studio 6.0 > DDK Documentation > Microsoft Windows NT 4.0 DDK > Graphics Drivers > Design Guide > Part 3: Print Components > Chapter 10 Supporting DDI Printing and User Interface Functions > Supporting Printer Interface Driver Functions

[MSDN Library June 1998] Optional Ease-of-Use Features (23.8904982282768%)

MSDN Library Visual Studio 6.0 > Specifications > Platforms > Windows Guidelines for Accessible Software Design > The Microsoft Windows Guidelines for Accessible Software Design