That is exactly was I was referring to with needing to know whether it was an origination stamp or what, ie the context of the stamp. That problem holds regardless of the format you store the stamp in, because even if there is a colloquial understanding of how to interpret a time change (1030 on Thursday is still 1030 on Thursday) it doesn't hold for every context (5 hrs from now is still 5 hours from now, except if when you said 5 hours from now you meant clock time)