Volume 6B, Motif Reference Manual, is a complete programmer's reference for the Motif toolkit. The Motif toolkit provides a complete set of widgets, such as buttons, scroll bars, menus, and dialog boxes, for developing graphical user interfaces. It also includes a library of functions for creating and manipulating those widgets. The second edition of the Motif Reference Manual covers Motif 2.1, the latest release of Motif. The contents of this book include: Reference pages for the widget classes defined by the Motif toolkit and the X Toolkit Intrinsics. Each reference page fully describes the widget's functionality, including its new and inherited resources, callback routines, and translations. Documentation on all of the Motif functions and macros that create and manipulate widgets and other Motif data types, such as compound strings and render tables. Reference material for the Motif Window Manager (mwm), a window manager designed to be compatible with the appearance and behavior of the Motif widget set. Descriptions of all the data types used by Motif functions. A list of all the new widget classes, functions, and widget resources in Motif 2.1 and 2.0. This book is designed to be used with Volume 6A, Motif Programming Manual, which describes how to build applications using the Motif toolkit and provides a complete tutorial with programming examples. Both of these books are an integral part of the X Window System series from O'Reilly.