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   This file is part of the GNU C Library.

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   modify it under the terms of the GNU Lesser General Public
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   version 2.1 of the License, or (at your option) any later version.

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   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

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   02111-1307 USA.

The example below show the rules for a timezone called MYST (made of MY%sT and S) and MYDT (made of MY%sT and D).

# Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
Rule	ABC	2003	max	-	Oct	lastSun	2:00	0	S
Rule	ABC	2003	max	-	Apr	Sun>=1	2:00	1:00	D
# Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
Zone tz_custom	-3:00	ABC	MY%sT

The rules are:DST is to be turned on starting on the 1st sunday on after the april 1st (Apr Sun>=1) at 2AM wall clock time (sometimes local time) and turned off the last sunday of october.
These rule being applicable from 2003 and on.
The lines beginning with the sign '#' are comments lines

This file must be named "customrules". It must coopied to the ntp directory of the module using an ftp client UserID = ntpupdate, password = ntpupdate. When the NTP componenet is reconfigured or the module is power cycled, 
the file customrules is read and a new tz_custom binary file is created (or overwrite the old one) on the same directory. Do not edit that file.



  Rule
     A rule line has the form:

     The fields that make up a rule line are:
     Rule   NAME  FROM  TO  TYPE  IN   ON     AT   SAVE  LETTER/S

for ex:
     Rule   USA   1969  1973   -  Apr lastSun 2:00  1:00   D

     NAME  Gives the (arbitrary) name of the set  of  rules  this
           rule is part of.

     FROM  Gives the first year in which the  rule  applies.  The
           word  minimum  (or  an abbreviation) means the minimum
           year with a representable time value. The word maximum
           (or  an  abbreviation)  means  the maximum year with a
           representable time value.

     TO    Gives the final year in which  the  rule  applies.  In
           addition  to  minimum and maximum (as above), the word
           only (or an abbreviation) can be used  to  repeat  the
           value of the FROM field.


     TYPE  Must be '-'

     IN    Names the month in which the rule takes effect.  Month
           names can be abbreviated.

     ON    Gives the day on which the rule takes  effect.  Recog-
           nized forms include:

            5    the fifth day of the month

           lastSun
                 The last Sunday in the month

           lastMon
                 The last Monday in the month

           Sun>=8
                 First Sunday on or after the eighth

           Sun<=25

                 Last Sunday on or before the 25th

           Names of days  of  the  week  can  be  abbreviated  or
           spelled  out  in  full.  Note:  There cannot be spaces
           within the ON field.

     AT    Gives the time of day at which the rule takes  effect.
           Recognized forms include:

            2    Time in hours

           2:00  Time in hours and minutes

           15:00 24-hour format time (for times after noon)

           1:28:14
                 Time in hours, minutes, and seconds, where  hour
                 0  is  midnight at the start of the day and hour
                 24 is midnight at the end of the day.

           Any of these forms can be followed by the letter w  if
           the  given  time  is local "wall clock" time; s if the
           given time is local "standard" time; or u (or g or  z)
           if the given time is universal time. In the absence of
           an indicator, wall clock time is assumed.

     SAVE  Gives the amount of time to be added to local standard
           time  when  the  rule is in effect. This field has the
           same format as the AT field (without the w and s  suf-
           fixes).

     LETTER/S
           Gives the "variable part" (for example, the "S" or "D"
           in  "EST"  or  "EDT"  of time zone abbreviations to be
           used when this rule is in effect.  If  this  field  is
           '-', the variable part is null.

  Zone
     A zone line has the form:

     Zone  NAME                 GMTOFF  RULES/SAVE   FORMAT  [UNTIL]

for ex:
     Zone tz_custom             9:30        -         CST    1992 Mar 15 12:00
                                8:30      Aus         CST

     The fields that make up a zone line are:

     NAME  must be tz_custom

     GMTOFF
           The amount of time to add to UTC to get standard  time
           in this zone. This field has the same format as the AT
           and SAVE fields of rule lines; begin the field with  a
           minus sign to subtract time from UTC.

     RULES/SAVE
           The name of the rule(s) that apply in  the  time  zone
           or,  alternately,  an  amount  of time to add to local
           standard time. If this field  is  `-',  then  standard
           time always applies in the time zone.

     FORMAT
           The format for time zone abbreviations  in  this  time
           zone.  The pair of characters %s is used to show where
           the "variable part"  of  the  time  zone  abbreviation
           goes.  Alternately, a slash (/) separates standard and
           daylight abbreviations.

     UNTIL The time at which the UTC offset or the rule(s) change
           for  a location. It is specified as a year, a month, a
           day, and a time of day. The time of day has  the  same
           format  as  the  AT  field  of  rule lines. If this is
           specified, the time zone information is generated from
           the  given  UTC  offset and rule change until the time
           specified.

           The month, day, and time of day have the  same  format
           as  the  IN,  ON,  and  AT columns of a rule; trailing
           columns can be omitted, and default  to  the  earliest
           possible value for the missing columns.

           The next line must be a "continuation" line. This line
           has  the  same  form  as  a  zone line except that the
           string "Zone" and the name are omitted. The  continua-
           tion  line  places  information  starting  at the time
           specified as the UNTIL field in the previous  line  in
           the file used by the previous line. Continuation lines
           can contain an UNTIL field, just  as  zone  lines  do,
           indicating  that  the next line is a further continua-
           tion.
