Run1 Run2 Run3 Run4 Average SDF Append 12.15 11.13 10.98 10.94 11.30 SDF->DBF, DBF Append 13.10 13.52 12.44 12.88 12.99>>Well, I wrote a program that will do this. It still needs some tweaking, like checking for file existance and such. However, I don't think you'll see any speed improvements by doing this and performing a DBF APPEND over doing an SDF APPEND to begin with, since there will be some time involved in getting the DBF created from the SDF file. However, it was a good learning experience. Most of the info I got came from what everyone has posted in this thread, plus looking in the help under "Table File Structure". I think there may be a typo there. For the last bit of reserved bytes in the field header portion, it says it goes from bytes 19-32, but since they start at 0 and the field header is supposed to be 32 bytes, it should probably read as going from bytes 19-31.