TimeStamp is a read-only DisplayString giving a human-readable rendering of the same History time-stamp carried by TimeStampIndex for this row. It exists purely for convenience, so a person reading the table does not have to convert the raw seconds-since-1970 value in TimeStampIndex into a calendar date and clock time by hand. The MIB gives '14:58:15 05/Jun/2003' as an example of the hh:mm:ss dd/mmm/yyyy format this object uses, so an admin reading this mpsb table can tell exactly when the sample in that row — raw frame and byte traffic counters plus hardware/software error counts for that MAC-to-MAC conversation — was captured.