The particular UIObject which is responsible for getting text commands from the user, parsing them, and executing them. Each time it is requested to do so, this object will check to see if the user has entered a line of text at the VMD prompt, and if so, this will read in the command, break it up into the individual words, and determine what action is being requested. Every action in VMD which the user can request to have performed has a corresponding Command object associated with it, and a text command representation.
Each text command consists of N separate words separated by whitespace, with the first word in the command used to distinguish between different types of commands. The UIList maintains a list of these initial words, and with each word there is an associated callback function which is called when a text command is read in and the first word is found in the list.
This object can also be directed to read commands from a file, and to echo text commands to the console.
UIText is able to use the Tcl library, if available, to parse the text commands and to provide sophisticated interpreted script capabilities such as control loops, variable substitution, if-then-else constructs, and user-defined subroutines and functions. If Tcl is not available, this object will still function, but only the basic VMD commands will be understood.