Can you not find out how the field OHPODT is populated. Probably there should be a logic in some program which populates this field. This should give you an idea of the format.
I am guessing: Based on the field length being 7,0 i think this might be a CYYMMDD format. The First digit could be the ’1′ or ’0′. This might have come into existence because of some Y2K conversion where all the dates whose year part is greater than 40 were tagged as 0 and for those dates whose year is less than 40 tagged as 1.
I might be wrong as well. So the best thing would be to find out which of the programs populate this field and then look at the logic to identify the format.