[para] This facility requires the use of a tclsh that provides
[cmd {info frame}].  Otherwise, no [term #line] directives are emitted. The
command is supported by Tcl 8.5 and higher. It is also supported by
Tcl 8.4 provided that it was compiled with the define
[option -DTCL_TIP280]. An example of such is ActiveState's ActiveTcl.