The ".t8" just means a dataset file with 8 fields plus the date. It is not always the CONTRACT format. For avoiding confusion, we'll modify that example.

To the other questions: Yes, splitting options data over many datasets by their expiration dates would be less effective I suppose, if not to say crazy. Historical files are either not split, or split by years. Files or datasets are not updated unless you update them. We can not add 4-5 fields to the *.t8 file because it would then be a *.t12-*.t13 file.