Introduction.

The variables of the date and time is in the HEADER section.

$TDCREATE, $TDUCREATE, $TDUPDATE, and $TDUUPDATE variables was written in the form:
"Julian date"."Fraction of day"

$TDCREATE and $TDUPDATE are based on the local date and time, $TDUCREATE and $TDUUPDATE are based on universal date and time(UTC).

An example C source code for local date and time translation:


/* Julian date + Fraction of day example,
Author: Copyright (C) 2013 by Paolo Caroni
License: GPLv2 or any later versions*/

#include <stdio.h>
#include <time.h>

int main(void)
{
   int JD;
   float fraction_day;
   time_t now;
   if (time(&now) != (time_t)(-1))
   {
      struct tm *current_time = localtime(&now);

      JD=current_time->tm_mday-32075+1461*(current_time->tm_year+6700+(current_time->tm_mon-13)/12)/4+367*(current_time->tm_mon-1-(current_time->tm_mon-13)/12*12)/12-3*((current_time->tm_year+6800+(current_time->tm_mon-13)/12)/100)/4;
      /* Transforms the current local gregorian date in a julian date.*/

      fraction_day=(current_time->tm_hour+(current_time->tm_min/60.0)+(current_time->tm_sec/3600.0))/24.0;
      /* Transforms the current local clock time in fraction of day.*/

      printf("local Julian date.Fraction of day\n%7.9f\n", JD+fraction_day);
   }
   return 0;
}


$TDINDWG and $TDUSRTIMER variables was written in the form:
"Number of days"."Fraction of day"