XSPEC/Tcl script files can be executed in one of two ways. If you give a script file name as an argument for XSPEC, XSPEC will execute that script file, and then exit. Within XSPEC, script files can be executed using the source command (see the help entry on the source command). Tcl does not have default file name extensions so the entire file name of the script file must be given explicitly.
Given the differences in how models are stored between the current version of XSPEC and that of versions 9.02 and earlier, a perl script file has been produced to convert script files from XSPEC version 9.02 and earlier into a format that will run under the current version of XSPEC. This script is called xs_update.pl and can be found in the directory $ XANADU/spectral/xspec/src/tools (XANADU:[spectral.xspec.src.tools] for VMS users). The script does command name completion and conversion of the model specification format. Where necessary, the script file issues warning messages when the user my need to edit the file by hand to ensure the converted script behaves as desired.