What is happenning and how to fix it: If you have been using XBuild to construct your experiment (X-) files, the 3-digit code is more than the program was designed to handle. For complex experiment files, a text editor (Ultra Edit is popular where I work but Windows TextPad will usually work) will come in handy. The problem is that XBuild pads the space between the treatment description, "TName", and the number of the cultivar treatment/level, "CU", when building the table of treatments in the X-File (Description and Cultivar if you are looking at the TREATMENTS page in XBuild). This formats the line properly for 1- or 2-digit cultivar levels but shifts all of the subsequent fields 1 space too far to the right when you have a 3-digit cultivar level (100-999 cultivars) in an experiment. This causes DSSAT to mis-read all treatments with 3-digits, resulting in the error message that you see. The fix is straightforward - just remove the extra space. Open your X-file in a text editor and scroll down to the Treatments table (*TREATMENTS). Look down through the list of treatments. Once you get to treatment number 100 you will see that all fields from "CU" to "SM" are shifted one space farther tho the right than the treatments listed above them. Use the arrow keys to move the cursor just in front of the 1 in 100 in the CU column (your 1st 3-digit level). If your text editor lists rows and columns, you should be in column 36. Now, hit the backspace key to shift the rest of the line left 1 space. All columns in that row should now line up with those above them. Repeat this for all 3-digit levels and save the file. DSSAT should now run them just fine. If you are using a text editor for the first time, make sure it doesn't add ".TXT" to the end of the file name or DSSAT probably won't recognize it. XBiuld lists the cultivar levels properly in the *CULTIVAR section so no further editing is required. IMPORTANT NOTE: DO NOT EDIT THIS FILE IN XBUILD EVER AGAIN! If you load the modified X-file into XBuild, you will see that XBuild has dropped the first 2 digits of your 3-digit cultivar levels (ex. what was 107 now appears as 7 in the treatments page). If you then save the file, the first 2 digits will be lost. When you open the X-file in a text editor, the treatments will go something like this: 98, 99, 0, 1, 2, 3... and you will have to re-edit all 3-digit levels to insert the first 2 digits of each. Good Luck, Stu Stuart Rymph Post-Doctoral Research Assistant University of Wisconsin University of Florida [log in to unmask]