The Tcl/Tk combination is increasingly popular because it lets you produce sophisticated graphical interfaces with a few easy commands, develop and change scripts quickly, and conveniently tie together existing utilities or programming libraries. The Tcl/Tk Pocket Reference ,a handy reference guide to the basic Tcl language elements, Tcl and Tk commands, and Tk widgets, is a companion volume to Tcl/Tk in a Nutshell . Paul Raines is a physicist and scientific programmer at the Stanford Linear Accelerator Center at Stanford University where he is part of a large collaboration studying CP violation (why charge and parity are not conserved in some particle decays). He is a huge advocate of scripting languages and has been using Tcl on various projects since 1992. He is also the coauthor of O'Reilly & Associates' Tcl/Tk in a Nutshell. When he can get away from the lab, Paul enjoys hiking, bridge, and soccer.