Sorry - I was traveling. The official link that I can get to for the 5.4 Help Center take on FOSI support is: http://www.ptc.com/ae54f000_hc/ati_mil_prf_support/28001C.htm If you cannot access this link, then I suggest searching for "Arbortext's MIL-PRF-28001C Support" in the online help of the product version you are using. I did this with the V5.3 help center and came up with 3 hits - the last of which: http://localhost:60239/fosi_support/28001C.htm?queryId=12399fded57 (change your localhost port, if necessary) is titled MIL-PRF-28001C - Appendix B. This is the stuff you want, as the annotations in the Appendix are R&D's notes about what is, and is not supported in the FOSI standard. As for writing a FOSI, you'll need to go to either: http://www.ptc.com/ae54f000_hc/aeFosi/sect1sect1.html in the 5.4 help center, or to this link in the 5.3 help center: http://localhost:60239/ae_help/help63.html (Change your localhost port if necessary.) if neither of these links work for you, you can also access the FOSI help in the 5.3 help center via searching for "FOSI stylesheets". The link above popped up as the second hit in the search for me. Hope this helps. -Jean