The heart of the system is the ability to create an embedded Tcl
interpreter with which the Prolog system can interact.
A Tcl interpreter is created within Prolog through a call to
which creates a new interpreter, initializes it, and returns a reference to it in the variable TclInterpreter. The reference can then be used in subsequent calls to manipulate the interpreter. More than one Tcl interpreter object can be active in the Prolog system at any one time.