Volume Five, X Toolkit Intrinsics Reference Manual , is a complete programmer's reference for X Toolkit (Xt). Xt is a library of C language routines designed to facilitate the design of the user interfaces, with reusable components called widgets. This book covers the X Toolkit Intrinsics in depth and contains reference pages for the Athena widgets. Contents include: Reference pages for each of the Xt Intrinsics and macros, organized alphabetically for ease of reference Reference pages for the Core, Composite, Constraint and Shell widget classes defined by Xy Reference pages for the function prototypes used to declare widget methods and other internal functions Reference pages for the Athena widgetsPermuted index Master index for Volumes Four and Five Numerous appendices and quick reference aids This book is designed to be used the Volume Four, X Toolkit Intrinsics Programming Manual, which describes how to build applications using the Xt Intrinsics and provides a complete tutorial with programming examples.