Yeah, so StringTheory has a pair of classes called StringFormat and StringDeformat. It slso supports Extended Pictures - basically just more picture formats than the base Clarion Set.
The timestamp format you are refering to is known as the Unix Epoch. This is either the number of seconds, or milliseconds, since Jan 1, 1970. I recommend using a REAL value for this number.
If you want to convert Unix Epoch time to a Clarion Date and Clarion Time (or vice versa) then StringTheory also has a class to do that. So storing the data as a single REAL value, or twin LONG values, is easy.