Timestamp
A timestamp is a 
six or
seven
part value (year, month, day, hour, minute, second, and optional
fractional second) that represents a date and time.
The time portion of a timestamp value can
include a specification of fractional seconds. The number of digits
in the fractional seconds is specified using an attribute in the range
from 0 to 12 with a default of 6
The internal representation
of a timestamp is a string of between 7 and 13 bytes.
The first 4 bytes represent the date, the next 3 bytes the time, and
the last 0 to 6 bytes the fractional seconds.