This book is a comprehensive description of the Smalltalk classes and methods at the center of the VAST Platform (VA Smalltalk). It includes examples, syntax, and semantic summaries that show how to use the Smalltalk classes. It covers such topics as Common Language Implementation, Common Language Data Types, Common and Extended Widgets, Common Graphics, Common File System, Common Process Model, the Socket Communications Interface, the virtual machine API, the implementation of national language support (NLS), inter-process communication (IPC), and object linking and imbedding (OLE).