The first three questions that a user might ask about any new version of an existing program-particularly
one going through radical changes are:
Can I still do with it all the things I am used to being able to do?
What can I do now that I couldn't do before?
What will I be able to do in the future as a result of the changes?
These questions are answered in more details on some of the other pages on this site, specifically the 11 vs 12, Science, and Future pages (this page is here so you don't have to hunt all over for this
Briefly however, XSPEC12 when the final release is ready will implement the full command set of XSPEC11 apart from some
previously declared deprecated features. Perhaps the most significant of these is that the older
model entry syntax will not be supported. Other deletions include commands related to writing history/save sets in the
older "sf" format. We have not taken a final decision on whether to support the sf and Einstein FITS data
formats in XSPEC12: they will not be available in the beta release, however.
We stress that XSPEC will continue to support user model development in fortran (but now also support C and C++), but with