Imported upstream version 1.3rc6.

[pkg-rrdtool.git] / doc / rrdgraph_graph.1

.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings.  \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote.  \*(C+ will
.\" give a nicer C++.  Capital omega is used to do unbreakable dashes and
.\" therefore won't be available.  \*(C` and \*(C' expand to `' in nroff,
.\" nothing in troff, for use with C<>.
.tr \(*W-
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
.    ds -- \(*W-
.    ds PI pi
.    if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
.    if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\"  diablo 12 pitch
.    ds L" ""
.    ds R" ""
.    ds C` ""
.    ds C' ""
'br\}
.el\{\
.    ds -- \|\(em\|
.    ds PI \(*p
.    ds L" ``
.    ds R" ''
'br\}
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
.\" entries marked with X<> in POD.  Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.if \nF \{\
.    de IX
.    tm Index:\\$1\t\\n%\t"\\$2"
..
.    nr % 0
.    rr F
.\}
.\"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.hy 0
.if n .na
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear.  Run.  Save yourself.  No user-serviceable parts.
.    \" fudge factors for nroff and troff
.if n \{\
.    ds #H 0
.    ds #V .8m
.    ds #F .3m
.    ds #[ \f1
.    ds #] \fP
.\}
.if t \{\
.    ds #H ((1u-(\\\\n(.fu%2u))*.13m)
.    ds #V .6m
.    ds #F 0
.    ds #[ \&
.    ds #] \&
.\}
.    \" simple accents for nroff and troff
.if n \{\
.    ds ' \&
.    ds ` \&
.    ds ^ \&
.    ds , \&
.    ds ~ ~
.    ds /
.\}
.if t \{\
.    ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
.    ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
.    ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
.    ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
.    ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
.    ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
.    \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.    \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
.    \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
.    ds : e
.    ds 8 ss
.    ds o a
.    ds d- d\h'-1'\(ga
.    ds D- D\h'-1'\(hy
.    ds th \o'bp'
.    ds Th \o'LP'
.    ds ae ae
.    ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "RRDGRAPH_GRAPH 1"
.TH RRDGRAPH_GRAPH 1 "2008-03-15" "1.3rc6" "rrdtool"
.SH "NAME"
rrdgraph_graph \- rrdtool graph command reference
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fB\s-1PRINT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fIformat\fR
.PP
\&\fB\s-1GPRINT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fIformat\fR
.PP
\&\fB\s-1COMMENT\s0\fR\fB:\fR\fItext\fR
.PP
\&\fB\s-1VRULE\s0\fR\fB:\fR\fItime\fR\fB#\fR\fIcolor\fR[\fB:\fR\fIlegend\fR][\fB:dashes\fR[\fB=\fR\fIon_s\fR[,\fIoff_s\fR[,\fIon_s\fR,\fIoff_s\fR]...]][\fB:dash\-offset=\fR\fIoffset\fR]]
.PP
\&\fB\s-1HRULE\s0\fR\fB:\fR\fIvalue\fR\fB#\fR\fIcolor\fR[\fB:\fR\fIlegend\fR][\fB:dashes\fR[\fB=\fR\fIon_s\fR[,\fIoff_s\fR[,\fIon_s\fR,\fIoff_s\fR]...]][\fB:dash\-offset=\fR\fIoffset\fR]]
.PP
\&\fB\s-1LINE\s0\fR[\fIwidth\fR]\fB:\fR\fIvalue\fR[\fB#\fR\fIcolor\fR][\fB:\fR[\fIlegend\fR][\fB:STACK\fR]][\fB:dashes\fR[\fB=\fR\fIon_s\fR[,\fIoff_s\fR[,\fIon_s\fR,\fIoff_s\fR]...]][\fB:dash\-offset=\fR\fIoffset\fR]]
.PP
\&\fB\s-1AREA\s0\fR\fB:\fR\fIvalue\fR[\fB#\fR\fIcolor\fR][\fB:\fR[\fIlegend\fR][\fB:STACK\fR]]
.PP
\&\fB\s-1TICK\s0\fR\fB:\fR\fIvname\fR\fB#\fR\fIrrggbb\fR[\fIaa\fR][\fB:\fR\fIfraction\fR[\fB:\fR\fIlegend\fR]]
.PP
\&\fB\s-1SHIFT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fIoffset\fR
.PP
\&\fB\s-1TEXTALIGN\s0\fR\fB:\fR{\fBleft\fR|\fBright\fR|\fBjustified\fR|\fBcenter\fR}
.PP
\&\fB\s-1PRINT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fI\s-1CF\s0\fR\fB:\fR\fIformat\fR (deprecated)
.PP
\&\fB\s-1GPRINT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fI\s-1CF\s0\fR\fB:\fR\fIformat\fR (deprecated)
.PP
\&\fB\s-1STACK\s0\fR\fB:\fR\fIvname\fR\fB#\fR\fIcolor\fR[\fB:\fR\fIlegend\fR] (deprecated)
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
These instructions allow you to generate your image or report.
If you don't use any graph elements, no graph is generated.
Similarly, no report is generated if you don't use print options.
.SH "PRINT"
.IX Header "PRINT"
.IP "\fB\s-1PRINT:\s0\fR\fIvname\fR\fB:\fR\fIformat\fR[\fB:strftime\fR]" 4
.IX Item "PRINT:vname:format[:strftime]"
Depending on the context, either the value component or the time
component of a \fB\s-1VDEF\s0\fR is printed using \fIformat\fR. It is an error
to specify a \fIvname\fR generated by a \fB\s-1DEF\s0\fR or \fB\s-1CDEF\s0\fR.
.Sp
Any text in \fIformat\fR is printed literally with one exception:
The percent character introduces a formatter string. This string
can be:
.Sp
For printing values:
.RS 4
.IP "\fB%%\fR" 4
.IX Item "%%"
just prints a literal '%' character
.IP "\fB%#.#le\fR" 4
.IX Item "%#.#le"
prints numbers like 1.2346e+04. The optional integers # denote field
width and decimal precision.
.IP "\fB%#.#lf\fR" 4
.IX Item "%#.#lf"
prints numbers like 12345.6789, with optional field width
and precision.
.IP "\fB%s\fR" 4
.IX Item "%s"
place this after \fB%le\fR, \fB%lf\fR or \fB%lg\fR. This will be replaced by the
appropriate \s-1SI\s0 magnitude unit and the value will be scaled
accordingly (123456 \-> 123.456 k).
.IP "\fB%S\fR" 4
.IX Item "%S"
is similar to \fB%s\fR. It does, however, use a previously defined
magnitude unit. If there is no such unit yet, it tries to define
one (just like \fB%s\fR) unless the value is zero, in which case the magnitude
unit stays undefined. Thus, formatter strings using \fB%S\fR and no \fB%s\fR
will all use the same magnitude unit except for zero values.
.RE
.RS 4
.Sp
If you \s-1PRINT\s0 a \s-1VDEF\s0 value, you can also print the time associated with it by appending the string
\&\fB:strftime\fR to the format. Note that rrdtool uses the strftime function of your OSs clibrary. This means that
the conversion specifier may vary. Check the manual page if you are uncertain. The following is a list of
conversion specifiers usually supported across the board. 
.IP "\fB%a\fR" 4
.IX Item "%a"
The abbreviated weekday name according to the current locale.
.IP "\fB%A\fR" 4
.IX Item "%A"
The full weekday name according to the current locale.
.IP "\fB%b\fR" 4
.IX Item "%b"
The abbreviated month name according to the current locale.
.IP "\fB%B\fR" 4
.IX Item "%B"
The full month name according to the current locale.
.IP "\fB%c\fR" 4
.IX Item "%c"
The preferred date and time representation for the current locale.
.IP "\fB%d\fR" 4
.IX Item "%d"
The day of the month as a decimal number (range 01 to 31).
.IP "\fB%H\fR" 4
.IX Item "%H"
The hour as a decimal number using a 24\-hour clock (range 00 to 23).
.IP "\fB%I\fR" 4
.IX Item "%I"
The hour as a decimal number using a 12\-hour clock (range 01 to 12).
.IP "\fB%j\fR" 4
.IX Item "%j"
The day of the year as a decimal number (range 001 to 366).
.IP "\fB%m\fR" 4
.IX Item "%m"
The month as a decimal number (range 01 to 12).
.IP "\fB%M\fR" 4
.IX Item "%M"
The minute as a decimal number (range 00 to 59).
.IP "\fB%p\fR" 4
.IX Item "%p"
Either `\s-1AM\s0' or `\s-1PM\s0' according to the given time value, or the corresponding
strings for the current locale.  Noon is treated as `pm' and midnight as
`am'.  Note that in many locales and `pm' notation is unsupported and in
such cases \f(CW%p\fR will return an empty string.
.IP "\fB%S\fR" 4
.IX Item "%S"
The second as a decimal number (range 00 to 61).
.IP "\fB%U\fR" 4
.IX Item "%U"
The  week  number  of  the current year as a decimal number, range 00 to 53, starting with the
first Sunday as the first day of week 01. See also \f(CW%V\fR and \f(CW%W\fR.
.IP "\fB%V\fR" 4
.IX Item "%V"
The \s-1ISO\s0 8601:1988 week number of the current year as a decimal number, range 01 to  53,  where
week  1 is the first week that has at least 4 days in the current year, and with Monday as the
first day of the week. See also \f(CW%U\fR and \f(CW%W\fR.
.IP "\fB%w\fR" 4
.IX Item "%w"
The day of the week as a decimal, range 0 to 6, Sunday being 0.  See also \f(CW%u\fR.
.IP "\fB%W\fR" 4
.IX Item "%W"
The week number of the current year as a decimal number, range 00 to  53,  starting  with  the
first Monday as the first day of week 01.
.IP "\fB%x\fR" 4
.IX Item "%x"
The preferred date representation for the current locale without the time.
.IP "\fB%X\fR" 4
.IX Item "%X"
The preferred time representation for the current locale without the date.
.IP "\fB%y\fR" 4
.IX Item "%y"
The year as a decimal number without a century (range 00 to 99).
.IP "\fB%Y\fR" 4
.IX Item "%Y"
The year as a decimal number including the century.
.IP "\fB%Z\fR" 4
.IX Item "%Z"
The time zone or name or abbreviation.
.IP "\fB%%\fR" 4
.IX Item "%%"
A literal `%' character.
.RE
.RS 4
.RE
.IP "\fB\s-1PRINT:\s0\fR\fIvname\fR\fB:\fR\fI\s-1CF\s0\fR\fB:\fR\fIformat\fR" 4
.IX Item "PRINT:vname:CF:format"
\&\fIDeprecated. Use the new form of this command in new scripts.\fR
The first form of this command is to be used with \fB\s-1CDEF\s0\fR \fIvname\fRs.
.SH "GRAPH"
.IX Header "GRAPH"
.IP "\fB\s-1GPRINT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fIformat\fR" 4
.IX Item "GPRINT:vname:format"
This is the same as \f(CW\*(C`PRINT\*(C'\fR, but printed inside the graph.
.IP "\fB\s-1GPRINT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fI\s-1CF\s0\fR\fB:\fR\fIformat\fR" 4
.IX Item "GPRINT:vname:CF:format"
\&\fIDeprecated. Use the new form of this command in new scripts.\fR
This is the same as \f(CW\*(C`PRINT\*(C'\fR, but printed inside the graph.
.IP "\fB\s-1COMMENT\s0\fR\fB:\fR\fItext\fR" 4
.IX Item "COMMENT:text"
Text is printed literally in the legend section of the graph. Note that in
RRDtool 1.2 you have to escape colons in \s-1COMMENT\s0 text in the same way you
have to escape them in \fB*PRINT\fR commands by writing \fB'\e:'\fR.
.IP "\fB\s-1VRULE\s0\fR\fB:\fR\fItime\fR\fB#\fR\fIcolor\fR[\fB:\fR\fIlegend\fR][\fB:dashes\fR[\fB=\fR\fIon_s\fR[,\fIoff_s\fR[,\fIon_s\fR,\fIoff_s\fR]...]][\fB:dash\-offset=\fR\fIoffset\fR]]" 4
.IX Item "VRULE:time#color[:legend][:dashes[=on_s[,off_s[,on_s,off_s]...]][:dash-offset=offset]]"
Draw a vertical line at \fItime\fR.  Its color is composed from three
hexadecimal numbers specifying the rgb color components (00 is off, \s-1FF\s0 is
maximum) red, green and blue followed by an optional alpha. Optionally, a legend box and string is
printed in the legend section. \fItime\fR may be a number or a variable
from a \fB\s-1VDEF\s0\fR. It is an error to use \fIvname\fRs from \fB\s-1DEF\s0\fR or \fB\s-1CDEF\s0\fR here.
Dashed lines can be drawn using the \fBdashes\fR modifier. See \fB\s-1LINE\s0\fR for more
details.
.IP "\fB\s-1HRULE\s0\fR\fB:\fR\fIvalue\fR\fB#\fR\fIcolor\fR[\fB:\fR\fIlegend\fR][\fB:dashes\fR[\fB=\fR\fIon_s\fR[,\fIoff_s\fR[,\fIon_s\fR,\fIoff_s\fR]...]][\fB:dash\-offset=\fR\fIoffset\fR]]" 4
.IX Item "HRULE:value#color[:legend][:dashes[=on_s[,off_s[,on_s,off_s]...]][:dash-offset=offset]]"
Draw a horizontal line at \fIvalue\fR.  \s-1HRULE\s0 acts much like \s-1LINE\s0 except that
will have no effect on the scale of the graph. If a \s-1HRULE\s0 is outside the
graphing area it will just not be visible.
.IP "\fB\s-1LINE\s0\fR[\fIwidth\fR]\fB:\fR\fIvalue\fR[\fB#\fR\fIcolor\fR][\fB:\fR[\fIlegend\fR][\fB:STACK\fR]][\fB:dashes\fR[\fB=\fR\fIon_s\fR[,\fIoff_s\fR[,\fIon_s\fR,\fIoff_s\fR]...]][\fB:dash\-offset=\fR\fIoffset\fR]]" 4
.IX Item "LINE[width]:value[#color][:[legend][:STACK]][:dashes[=on_s[,off_s[,on_s,off_s]...]][:dash-offset=offset]]"
Draw a line of the specified width onto the graph. \fIwidth\fR can be a
floating point number. If the color is not specified, the drawing is done
\&'invisibly'. This is useful when stacking something else on top of this
line. Also optional is the legend box and string which will be printed in
the legend section if specified. The \fBvalue\fR can be generated by \fB\s-1DEF\s0\fR,
\&\fB\s-1VDEF\s0\fR, and \fB\s-1CDEF\s0\fR.  If the optional \fB\s-1STACK\s0\fR modifier is used, this line
is stacked on top of the previous element which can be a \fB\s-1LINE\s0\fR or an
\&\fB\s-1AREA\s0\fR.
.Sp
The \fBdashes\fR modifier enables dashed line style. Without any further options
a symmetric dashed line with a segment length of 5 pixels will be drawn. The
dash pattern can be changed if the \fBdashes=\fR parameter is followed by either
one value or an even number (1, 2, 4, 6, ...) of positive values. Each value
provides the length of alternate \fIon_s\fR and \fIoff_s\fR portions of the
stroke. The \fBdash-offset\fR parameter specifies an \fIoffset\fR into the pattern
at which the stroke begins.
.Sp
When you do not specify a color, you cannot specify a legend.  Should
you want to use \s-1STACK\s0, use the \*(L"LINEx:<value>::STACK\*(R" form.
.IP "\fB\s-1AREA\s0\fR\fB:\fR\fIvalue\fR[\fB#\fR\fIcolor\fR][\fB:\fR[\fIlegend\fR][\fB:STACK\fR]]" 4
.IX Item "AREA:value[#color][:[legend][:STACK]]"
See \fB\s-1LINE\s0\fR, however the area between the x\-axis and the line will
be filled.
.IP "\fB\s-1TICK\s0\fR\fB:\fR\fIvname\fR\fB#\fR\fIrrggbb\fR[\fIaa\fR][\fB:\fR\fIfraction\fR[\fB:\fR\fIlegend\fR]]" 4
.IX Item "TICK:vname#rrggbb[aa][:fraction[:legend]]"
Plot a tick mark (a vertical line) for each value of \fIvname\fR that is
non-zero and not *UNKNOWN*. The \fIfraction\fR argument specifies the length of
the tick mark as a fraction of the y\-axis; the default value is 0.1 (10% of
the axis). Note that the color specification is not optional. The \s-1TICK\s0 marks normaly
start at the lower edge of the graphing area. If the fraction is negative they start
at the upper border of the graphing area.
.IP "\fB\s-1SHIFT\s0\fR\fB:\fR\fIvname\fR\fB:\fR\fIoffset\fR" 4
.IX Item "SHIFT:vname:offset"
Using this command \fBRRDtool\fR will graph the following elements
with the specified offset.  For instance, you can specify an
offset of (\ 7*24*60*60\ =\ )\ 604'800\ seconds to \*(L"look back\*(R" one
week. Make sure to tell the viewer of your graph you did this ...
As with the other graphing elements, you can specify a number or
a variable here.
.IP "\fB\s-1TEXTALIGN\s0\fR\fB:\fR{\fBleft\fR|\fBright\fR|\fBjustified\fR|\fBcenter\fR}" 4
.IX Item "TEXTALIGN:{left|right|justified|center}"
Labels are placed below the graph. When they overflow to the left, they wrap
to the next line. By default, lines are justified left and right. The
\&\fB\s-1TEXTALIGN\s0\fR function lets you change this default. This is a command and
not an option, so that you can change the default several times in your
argument list.
.IP "\fB\s-1STACK\s0\fR\fB:\fR\fIvname\fR\fB#\fR\fIcolor\fR[\fB:\fR\fIlegend\fR]" 4
.IX Item "STACK:vname#color[:legend]"
\&\fIDeprecated.  Use the \f(BI\s-1STACK\s0\fI modifiers on the other commands.\fR
.PP
\&\fBSome notes on stacking\fR
.PP
When stacking, an element is not placed above the X\-axis but rather
on top of the previous element.  There must be something to stack
upon.
.PP
You can use an \fBinvisible\fR \s-1LINE\s0 or \s-1AREA\s0 to stacked upon.
.PP
An \fBunknown\fR value makes the entire stack unknown from that moment on.
You don't know where to begin (the unknown value) and therefore do
not know where to end.
.PP
If you want to make sure you will be displaying a certain variable,
make sure never to stack upon the unknown value.  Use a \s-1CDEF\s0 instruction
with \fB\s-1IF\s0\fR and \fB\s-1UN\s0\fR to do so.
.SH "NOTES on legend arguments"
.IX Header "NOTES on legend arguments"
.Sh "Escaping the colon"
.IX Subsection "Escaping the colon"
A colon ':' in a \fIlegend\fR argument will mark the end of the
legend. To enter a ':' as part of a legend, the colon must be escaped
with a backslash '\e:'.  Beware that many environments process
backslashes themselves, so it may be necessary to write two
backslashes in order to one being passed onto rrd_graph.
.Sh "String Formatting"
.IX Subsection "String Formatting"
The text printed below the actual graph can be formatted by appending special
escape characters at the end of a text. When ever such a character occurs,
all pending text is pushed onto the graph according to the character
specified.
.PP
Valid markers are: \fB\ej\fR for justified, \fB\el\fR for left aligned, \fB\er\fR for
right aligned, and \fB\ec\fR for centered. In the next section there is an
example showing how to use centered formatting.
.PP
\&\fB\en\fR is a valid alias for \fB\el\fR since incomplete parsing in earlier
versions of rrdtool lead to this behaviour and a number of people has been using it.
.PP
Normally there are two space characters inserted between every two items
printed into the graph. The space following a string can be suppressed by
putting a \fB\eg\fR at the end of the string. The \fB\eg\fR also ignores any space
inside the string if it is at the very end of the string. This can be used
in connection with \fB%s\fR to suppress empty unit strings.
.PP
.Vb 1
\& GPRINT:a:MAX:%lf%s\eg
.Ve
.PP
A special case is \s-1COMMENT:\s0\fB\es\fR which inserts some additional vertical space
before placing the next row of legends.
.PP
If you are using the proportional font in your graph, you can use tab
characters or the sequence \fB\et\fR to line-up legend elements. Note that
the tabs inserted are relative to the start of the current legend
element!
.PP
Since RRDtool 1.3 is using Pango for rending text, you can use Pango markup.
Pango uses the xml \fBspan\fR tags for inline formatting instructions.:
.PP
A simple example of a marked-up string might be: 
.PP
.Vb 1
\& <span foreground="blue" size="x\-large">Blue text</span> is <i>cool</i>!
.Ve
.PP
The complete list of attributes for the span tag (taken from the pango documentation):
.IP "\fBfont_desc\fR" 4
.IX Item "font_desc"
A font description string, such as \*(L"Sans Italic 12\*(R"; note that any other span attributes will override this description. So if you have \*(L"Sans Italic\*(R" and also a style=\*(L"normal\*(R" attribute, you will get Sans normal, not italic.
.IP "\fBfont_family\fR" 4
.IX Item "font_family"
A font family name
.IP "\fBface\fR" 4
.IX Item "face"
Synonym for font_family
.IP "\fBsize\fR" 4
.IX Item "size"
Font size in 1024ths of a point, or one of the absolute sizes 'xx\-small', 'x\-small', 'small', 'medium', 'large', 'x\-large', 'xx\-large', or one of the relative sizes 'smaller' or 'larger'. If you want to specify a absolute size, it's usually easier to take advantage of the ability to specify a partial font description using 'font_desc'; you can use font_desc='12.5' rather than size='12800'.
.IP "\fBstyle\fR" 4
.IX Item "style"
One of 'normal', 'oblique', 'italic'
.IP "\fBweight\fR" 4
.IX Item "weight"
One of 'ultralight', 'light', 'normal', 'bold', 'ultrabold', 'heavy', or a numeric weight
.IP "\fBvariant\fR" 4
.IX Item "variant"
\&'normal' or 'smallcaps'
.IP "\fBstretch\fR" 4
.IX Item "stretch"
One of 'ultracondensed', 'extracondensed', 'condensed', 'semicondensed', 'normal', 'semiexpanded', 'expanded', 'extraexpanded', 'ultraexpanded'
.IP "\fBforeground\fR" 4
.IX Item "foreground"
An \s-1RGB\s0 color specification such as '#00FF00' or a color name such as 'red'
.IP "\fBbackground\fR" 4
.IX Item "background"
An \s-1RGB\s0 color specification such as '#00FF00' or a color name such as 'red'
.IP "\fBunderline\fR" 4
.IX Item "underline"
One of 'none', 'single', 'double', 'low', 'error'
.IP "\fBunderline_color\fR" 4
.IX Item "underline_color"
The color of underlines; an \s-1RGB\s0 color specification such as '#00FF00' or a color name such as 'red'
.IP "\fBrise\fR" 4
.IX Item "rise"
Vertical displacement, in 10000ths of an em. Can be negative for subscript, positive for superscript.
.IP "\fBstrikethrough\fR" 4
.IX Item "strikethrough"
\&'true' or 'false' whether to strike through the text
.IP "\fBstrikethrough_color\fR" 4
.IX Item "strikethrough_color"
The color of strikethrough lines; an \s-1RGB\s0 color specification such as '#00FF00' or a color name such as 'red'
.IP "\fBfallback\fR" 4
.IX Item "fallback"
\&'true' or 'false' whether to enable fallback. If disabled, then characters will only be used from the closest matching font on the system. No fallback will be done to other fonts on the system that might contain the characters in the text. Fallback is enabled by default. Most applications should not disable fallback.
.IP "\fBlang\fR" 4
.IX Item "lang"
A language code, indicating the text language
.IP "\fBletter_spacing\fR" 4
.IX Item "letter_spacing"
Inter-letter spacing in 1024ths of a point.
.IP "\fBgravity\fR" 4
.IX Item "gravity"
One of 'south', 'east', 'north', 'west', 'auto'.
.IP "\fBgravity_hint\fR" 4
.IX Item "gravity_hint"
One of 'natural', 'strong', 'line'.
.PP
To save you some typing, there are also some shortcuts:
.IP "\fBb\fR" 4
.IX Item "b"
Bold
.IP "\fBbig\fR" 4
.IX Item "big"
Makes font relatively larger, equivalent to <span size=\*(L"larger\*(R">
.IP "\fBi\fR" 4
.IX Item "i"
Italic
.IP "\fBs\fR" 4
.IX Item "s"
Strikethrough
.IP "\fBsub\fR" 4
.IX Item "sub"
Subscript
.IP "\fBsup\fR" 4
.IX Item "sup"
Superscript
.IP "\fBsmall\fR" 4
.IX Item "small"
Makes font relatively smaller, equivalent to <span size=\*(L"smaller\*(R">
.IP "\fBtt\fR" 4
.IX Item "tt"
Monospace font
.IP "\fBu\fR" 4
.IX Item "u"
Underline 
.SH "SEE ALSO"
.IX Header "SEE ALSO"
rrdgraph gives an overview of how \fBrrdtool graph\fR works.
rrdgraph_data describes \fB\s-1DEF\s0\fR,\fB\s-1CDEF\s0\fR and \fB\s-1VDEF\s0\fR in detail.
rrdgraph_rpn describes the \fB\s-1RPN\s0\fR language used in the \fB?DEF\fR statements.
rrdgraph_graph page describes all of the graph and print functions.
.PP
Make sure to read rrdgraph_examples for tips&tricks.
.SH "AUTHOR"
.IX Header "AUTHOR"
Program by Tobias Oetiker <tobi@oetiker.ch>
.PP
This manual page by Alex van den Bogaerdt <alex@ergens.op.het.net>