[MSDN Library June 1998] Optional Parameter Specification for Excel's GET.CHART.ITEM() (53.4523809523809%)

MSDN Library Visual Studio 6.0 > Knowledge Base > Excel

[MSDN Library June 1998] Optional Features for Address Book Providers (20.4586260733802%)

MSDN Library Visual Studio 6.0 > Platform SDK > Database and Messaging Services > Messaging API (MAPI) > Guide > Developing an Address Book Provider

[MSDN Library June 1998] Optional Features Transport Providers Can Implement (19.8232857394677%)

MSDN Library Visual Studio 6.0 > Platform SDK > Database and Messaging Services > Messaging API (MAPI) > Guide > Developing a Transport Provider

[MSDN Library June 1998] Optional Interfaces for the Visual Designer (16.1952406236272%)

MSDN Library Visual Studio 6.0 > Tools and Technologies > ActiveX Designer Programmer's Reference > Chapter 3: Designing and Implementing an ActiveX Designer > Creating the Visual Designer

[MSDN Library June 1998] Optional Report Message Properties (16.1588263245426%)

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