#set TITLE = "dates"
#include top

.SH DESCRIPTION
Data containing dates may be plotted directly
and/or used in date arithmetic (using functions).
The allowable formats for dates are enumerated herein
(see KEY below for explanation of codes).  
.LP
\fBMonth, day, and year notations:\fR
.IP \(bu
\fCmmddyy\fR      (example: 033199)
.IP \(bu
\fCmm-dd-yy\fR      (example: 03-31-99)
.IP \(bu
\fCmm-dd-yyyy\fR      (example: 03-31-1999)
.IP \(bu
\fCmm/dd/yy\fR      (example: 03/31/99)
.IP \(bu
\fCdd-mm-yy\fR      (example: 31-03-99)
.IP \(bu
\fCdd/mm/yyyy\fR      (example: 31/03/99)
.IP \(bu
\fCddmmmyyyy\fR      (example: 31mar1999 or 31MAR99)
.IP \(bu
\fCdd-mmm-yy\fR      (example: 31-mar-99 or 31-MAR-99)
.IP \(bu
Others:
.nf
.ft C
mm/dd/yyyy  mmddyyyy      mm.dd.yy    mm.dd.yyyy
mmm-dd-yy   mmm-dd-yyyy   mmm_dd_yy   mmm_dd_yyyy
mmm/dd/yy   mmm/dd/yyyy

dd-mm-yy    dd-mm-yyyy    dd/mm/yy    dd/mm/yyyy
ddmmyy      dd.mm.yy      dd.mm.yyyy
dd-mmm-yyyy dd_mmm_yy     dd_mmm_yyyy
dd/mmm/yy   dd/mmm/yyyy   ddmmmyy     ddmmmyyyy

yy-mm-dd    yy/mm/dd      yymmdd      yy.mm.dd
yyyy-mm-dd  yyyy/mm/dd    yyyymmdd    yyyy.mm.dd
yyyy-mmm-dd yyyy_mmm_dd   yyyymmmdd
.fi
.LP
\fBMonth & year notations\fR
.br
(a day value of 01 is used internally for arithmetic/plotting purposes):
.IP \(bu
\fCyymm\fR      (example: 9903)
.IP \(bu
\fCmm/yyyy\fR      (example: 03/1999)
.IP \(bu
Others: \fC
yy/mm     yy-mm       yyyymm       yyyy/mm      yyyy-mm
mm/yy     mm-yy       mm-yyyy\fR 
.LP
\fBQuarter year notations\fR
.br
(day and month will be set to mid-quarter for arithmetic/plotting purposes):
.IP \(bu
\fCyyqn\fR      (example: 99q1 or 99Q1)
.IP \(bu
\fCnqyyyy\fR      (example: 1q1999 or 1Q1999)
.IP \(bu
Others:
\fCyyyyqn       nqyy    \fR
.LP
\fBYear only notation\fR
.IP \(bu
\fCyy\fR (uses pivot year, so 00 is greater than 99)


.SH DEFAULT NOTATION
The default notation is \fBmmddyy\fR, unless otherwise specified
in the ploticus
.ig >>
<a href="config.html">
.>>
configuration file
.ig >>
</a>
.>>
 .

.SH PLOTTING VARIOUS DATE NOTATIONS
To plot data having date notations other than the default, use the 
\fIformat\fR portion of the 
\fCxscaletype\fR or \fCyscaletype\fR attributes of
\fBproc areadef\fR or \fBproc defineunits\fR.
.br
For example:
.nf
.ft C
#proc areadef
  xscaletype: date mm/dd/yy
.ft R
.fi
.LP
\fBAlternate full-date notations:\fR
When using notations that do not contain a specific day 
(such as month year, quarter year, or year only) 
there may be occasions when it is necessary to specify an
exact day point (for example to create an annotation).
To do this, an alternate full date format may be used.
For example, if \fCyyqn\fR notation is being used,
full dates may be given in \fCyy/mm/dd\fR format.  
For an example this, see
.ig >>
<a href="../gallery/bars9.htm">
.>>
bars9 
.ig >>
</a>
.>>
.IP
.ft C
.nf
			Alternate full-
Notation 		date notation
-------------------	-----------
yymm			yymmdd
yymmm			ddmmmyy
yy/mm, yy-mm, etc.	yy/mm/dd
yyyy/mm, yyyy-mm, etc.	yyyy/mm/dd
yy			yymmdd
mm/yy, mm-yy, etc.	dd/mm/yy
mm/yyyy, mm-yyyy, etc.	dd/mm/yyyy
yyqn			yy/mm/dd
yyyyqn			yyyy/mm/dd
nqyy			yy/mm/dd
nqyyyy			yyyy/mm/dd
.ft R
.fi
.LP


.ft R
.ig >>
<a name=display></a>
.>>

.SH DISPLAY FORMATS
In addition to the above notations, 
the following additional notations may be used only for
displaying dates (such as with the stubformat 
attribute, for instance).  They may not be used for 
date plotting or arithmetic.
.LP
\fBFull dates for presentation:\fR 
.IP \(bu
\fCmonth_dd,_yyyy \fR(or \fCfull\fR) (example: March 31, 1999)
.IP \(bu
\fCmon_dd,_yyyy\fR      (example: Mar 31, 1999)
.IP \(bu
\fCdd_month,_yyyy\fR      (example: 31 March, 1999)
.IP \(bu
\fCdd_mon,_yyyy\fR      (example: 31 Mar, 1999)
.IP \(bu
\fCWww_dd_mon,_yyyy \fR(or \fCwfull\fR) (example: Wed 31 Mar, 1999)
.LP
\fBMonth & year only:\fR  \fCmmyy, mmyyyy\fR
.LP
\fBMonth & day only:\fR   \fCmmmdd, mmm/dd, mmm-dd, mmm_dd, mm/dd, mm-dd, mm_dd 
.LP
\fBYear only:\fR   \fC'yy, yyyy\fR 
.LP
\fBMonth only:\fR   \fCmmm, mm, m\fR 
.LP
\fBDay only:\fR   \fCdd d\fR 
.LP
\fBWeekday:\fR 
.IP \(bu
\fCW\fR (example: S M T W T F S) 
.IP \(bu
\fCWww\fR (example: Sun Mon Tue Wed Thu Fri Sat)


.SH KEY TO CODE ABBREVIATIONS
.br
\fCm\fR = single character month (use M for capitalized)
.br
\fCmm\fR = numeric month 01-12
.br
\fCmmm\fR = three-character month e.g. jan (use MMM for JAN or Mmm for Jan)
.br
\fCmon\fR = month abbreviation e.g. Jan
.br
\fCmonth\fR = full month e.g. January
.br
\fCdd\fR = numeric day 01-31
.br
\fCd\fR = numeric day 1-31
.br
\fCyy\fR = numeric year 00-99
.br
\fCyyyy\fR = numeric year 1800-up
.br
\fCw\fR = single character weekday (use W for capitalized)
.br
\fCwww\fR = three character weekday (use Www or WWW for capitalized)
.br
\fCn\fR = 1, 2, 3 or 4 (quarter year notations)
.br
\fCq\fR = the letter \fCq\fR or \fCQ\fR (quarter year notations)
.br
\fC_\fR (underscore) = space
.fi

.SH BASIC UNIT
The basic date unit is always a \fBday\fR, regardless
of which notation is in use.  Stub and tic increments
may be expressed in \fCmonths\fR or \fCyears\fR, if desired.


.SH DATE ARITHMETIC AND FORMATING NOTES
.LP
1. It is possible to omit weekends.  This is usually done
in business- or market-related plots.  To omit weekends,
set the \fComitweekends\fR attribute in 
.ig >>
<a href="datesettings.html">
.>>
proc datesettings
.ig >>
</a>
.>>

.LP 
2.  Conversion from two-digit dates to four  digit  dates  is
achieved  using  a  pivot year- any two digit year less than
this value is assumed to be 21st century.   The  pivot  year
(default  =  77) is adjustable in the ploticus 
.ig >>
<a href="config.html">
.>>
configuation file
.ig >>
</a>
.>>
or in 
.ig >>
<a href="datesettings.html">
.>>
proc datesettings
.ig >>
</a>
.>>
 

.LP 
3.  When three-character months are  used,  they  are  always
entered and stored as lower case; however the capitalization
of the "mmm" can be altered to control  the  way  dates  are
presented, e.g.  Mmm = Jan, MMM = JAN.
 
.LP
4.  "Lazy" dates may be used.
A lazy date has 00 as the day and/or month portion and is usually
used in situations where the day and/or month is unknown or unavailable.
When a lazy date is used in date arithmetic the
missing month and/or day is converted to 01.
By default, lazy dates are not permitted for date arithmetic.
They can be allowed by setting an attribute in
.ig >>
<a href="datesettings.html">
.>>
proc datesettings
.ig >>
</a>
.>>
 
.LP
5. Localization of date presentation parameters may be  done
in the ploticus
.ig >>
<a href="config.html">
.>>
configuration file
.ig >>
</a>
.>>
 .

.LP
6. There are a number of 
.ig >>
<a href="functions.html">
.>>
functions
.ig >>
</a>
.>>
for manipulating dates
that may be used in ploticus scripts.

.SH Y2K COMPLIANCE
Ploticus has been tested on a year=2000 machine and found
to be year 2000 compliant.

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