This is the time part of the Session Sender start time. When TWAMP Control is enabled, the Date and Time are converted to the NTP timestamp format as defined in RFC 1305 [REF13] to send in Request-TW-Session message. The first 32 bits are the seconds since 0h Jan 1 1900 and the second 32 bits is the fractional second and is the number of units of 200 picoseconds. If f3TwampSessionSenderStartTimeType is IMMEDIATE, this attribute is not applicable. If f3TwampSessionSenderStartTimeType is RELATIVE, this attribute is not applicable. If f3TwampSessionSenderStartTimeType is FIXED, this attribute is the time when to start the test.