The GMTTIMESTAMP data type is similar to the TIMESTAMP data
type, except that the values are interpreted as values in Greenwich Mean Time. GMTTIMESTAMP values
are defined in a similar way to TIMESTAMP values, for example:
DECLARE GetGMTTimeStamp GMTTIMESTAMP;
SET GetGMTTimeStamp = GMTTIMESTAMP '1999-12-31 23:59:59.999999';