But for various reasons, a time slot may have been written into previously. If data already exists in the slot, the routines check for differences in the data already in the slot and the data waiting to be written there. If the data is identical, nothing is written and the return status value is 3.
If the data is different, both the data in the slot and that waiting to be written are written out to a ".overlap" file in the same directory. The slot is then filled with char -1 (0xffff) to signal the abnormal condition existing for this time slot. The return status value is 1 in this case.
Finally, if it is found that the time slot is already filled with char -1 (see previous paragraph for why this would be), then the struct waiting to be written is written to the ".overlap" file, and a status value of 2 is returned. This is a very abnormal condition.
bruce