HEASoft and XSPEC are now available as conda packages. See details ....
Syntax
XSPEC is a command-driven, interactive program. You will see a prompt
XSPEC12>
whenever input is required. Command recall and inline editing are available using the arrow keys. XSPEC uses Tcl as its user interface, providing looping, conditionals, file I/O, and so on. For further details of the Tcl syntax, consult appendix A, and links therein.