Hi Roger, I don't think that there will be problems with the EXP file, but there could be with the data file as the end of line statements may not be there in the UNIX version and all the data may be on one line. If this is the case you will simply need to convert it to an 80 column per line format for it to work in DOS. If you do have problems, the first thing to check is that all the files (instrument parameter, data and exp) have 80 characters per line (this is a classic starting problem for new GSAS users). You can do this easily by opening it in Word (or non-Bill Gates editor) and using the 'view nonprint characters' button (the one that looks like '1P' ). There is a program in the first menu of GSAS (I forget the name) that pads ascii files with the extra spaces required. I hope that this is useful, -Andrew Does anyone know if it is possible to use the same *.EXP file on dos & UNIX (Linux) machines? If so, what changes must be made to the file? Thanks in advance, Roger Mason ____________________________________________________________________ Get your own FREE, personal Netscape WebMail account today at http://webmail.netscape.com.