### E Descriptions of Plotting Attributes

This appendix lists the available plotting attributes (see Plotting Styles and Attributes). Note, the default value included in each description is the value that will be used if no other default value is supplied (for instance within a defaults file). In particular, the standard Kappa default style files contained in \$KAPPA_DIR include alternative default values for several attributes which will be used in preference to those described below.

Individual applications may override the normal behaviour of particular attributes, in which case the description of the application will include details.

It is often useful to specify values for some of the attributes of the current Frame  when giving a plotting style (title, axis labels, etc.). These additional attributes are described in Appendix D.

#### Description:

This attribute controls the appearance of annotated axes by determining whether a border is drawn around regions corresponding to the valid co-ordinates.

If the Border value of a plot is non-zero, then this border will be drawn as part of the axes. Otherwise, the border is not drawn (although axis labels and tick marks will still appear, unless other relevant attributes indicate that they should not). The default behaviour is to draw the border if tick marks and numerical labels will be drawn around the edges of the plotting area (see the Labelling  attribute), but to omit it otherwise.

Type:
Integer (boolean).

#### Description:

This attribute determines the colour index used when drawing each element of of a plot. It takes a separate value for each graphical element so that, for instance, the setting "Colour(title)=2" causes the title to be drawn using colour index 2. Standard X colour names, space-separated floating-point RGB triples, or HTML colour codes (optionally using a "@" inplace of a "#" to avoid the code being interpreted as a comment within a style file) can also be specified, and the nearest available colour will be used if the requested colour is not currently in the palette.

The default behaviour is for all graphical elements to be drawn using Pen 1.

Type:
Integer.

#### Notes:

• For a list of the graphical elements available, see Section 7.1.

• If no graphical element is specified, (e.g. Colour instead of Colour(title)), then all graphical elements are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining whether curves representing co-ordinate axes should be drawn.

If drawn, these axis lines will pass through any tick marks associated with numerical labels drawn to mark values on the axes. The location of these tick marks and labels (and hence the axis lines) is determined by the LabelAt(axis)  attribute.

If the DrawAxes value is non-zero (the default), then axis lines will be drawn, otherwise they will be omitted.

Type:
Integer (boolean).

#### Notes:

• Axis lines are drawn independently of any co-ordinate grid lines (see the Grid  attribute) so grid lines may be used to substitute for axis lines if required.

• In some circumstances, numerical labels and tick marks are drawn around the edges of the plotting area (see the Labelling  attribute). In this case, the value of the DrawAxes attribute is ignored.

#### Description:

This attribute controls the appearance of annotated axes by determining what to draw for a spectral axis representing a dual sideband spectrum. The sideband selected using the SideBand attribute will always be annotated on the edge of the Plot selected using the Edge(axis) attribute. In addition, if the DrawDSB attribute is non-zero (the default) the other sideband will be annotated on the opposite edge of the Plot. If DrawDSB is zero, then the other sideband will not be annotated.
Type:
Integer (boolean).

#### Description:

This attribute controls the appearance of annotated axes by determining whether a title is drawn.

If the DrawTitle  value is non-zero (the default), then the title will be drawn, otherwise it will be omitted.

Type:
Integer (boolean).

#### Notes:

• The text used for the title is obtained from the Title  attribute.

• The vertical placement of the title can be controlled using the TitleGap  attribute.

#### Description:

This attribute controls the appearance of annotated axes by determining which edges are used for displaying numerical and descriptive axis labels. It takes a separate value for each physical axis so that, for instance, the setting Edge(2)=left  specifies which edge to use to display labels for the second axis.

The values left, top, right and bottom (or any abbreviation) can be supplied for this attribute. The default is usually bottom for the first axis and left for the second axis. However, if exterior labelling was requested (see the Labelling  attribute) but cannot be produced using these default Edge values, then the default values will be swapped if this enables exterior labelling to be produced.

Type:
String.

#### Notes:

• In some circumstances, numerical labels will be drawn along internal grid lines instead of at the edges of the plotting area (see the Labelling  attribute). In this case, the Edge attribute only affects the placement of the descriptive labels (these are drawn at the edges of the plotting area, rather than along the axis lines).

#### Description:

This attribute controls the appearance of annotated axes by determining whether or not the title at the top of the plot will include a second line giving the NDF name. The default value of zero results in the title containing only the text given by the Title attribute. A non-zero value will result in a second line containing the NDF name being added to the title.
Type:
Integer (boolean).

#### Description:

This attribute determines the character fount index used when drawing each element of a plot. It takes a separate value for graphical element so that, for instance, the setting Font(title)=2  causes the title to be drawn using fount number 2.

The range of integer fount indices available and the appearance of the resulting text is determined by the PGPLOT graphics package, but include:

(1)
A simple single-stroke fount (the default)
(2)
A roman fount
(3)
An italic fount
(4)
A script fount

Type:

Integer.

#### Notes:

• For a list of the graphical elements available, see Section 7.1.

• If no graphical element is specified, (e.g. Font instead of Font(title)), then all graphical elements are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining the interval between the major axis values at which (for example) major tick marks are drawn. It takes a separate value for each physical axis so that, for instance, the setting  Gap(2)=3.0  specifies the interval between major values along the second axis.

The Gap value supplied will usually be rounded to the nearest ‘nice’ value, suitable (e.g.) for generating axis labels, before use. To avoid this ‘nicing’ you should set an explicit format for the axis using the Format(axis)  or Digits/Digits(axis)  attribute. The default behaviour is for the application to generate its own Gap value when required, based on the range of axis values to be represented.

Type:
Floating point.

#### Notes:

• The Gap value should use the same units as are used internally for storing co-ordinate values on the corresponding axis. For example, with a celestial co-ordinate system, the Gap value should be in radians, not hours or degrees.

• If no axis is specified, (e.g. Gap instead of Gap(2)), then both axes are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining whether grid lines (a grid of curves marking the ‘major’ values on each axis) are drawn across the plotting area.

If the Grid attribute is non-zero, then grid lines will be drawn. Otherwise, short tick marks on the axes are used to mark the major axis values. The default behaviour is to use tick marks if the entire plotting area is filled by valid co-ordinates, but to draw grid lines otherwise.

Type:
Integer (boolean).

#### Notes:

• The spacing between major axis values, which determines the spacing of grid lines, may be set using the Gap(axis)  attribute.

#### Description:

This attribute controls the appearance of annotated axes by determining where numerical axis labels and associated tick marks are placed. It takes a separate value for each physical axis so that, for instance, the setting "LabelAt(2)=10.0"  specifies where the numerical labels and tick marks for the second axis should be drawn.

For each axis, the LabelAt value gives the value on the other axis at which numerical labels and tick marks should be placed. For example, in a celestial (right ascension, declination) co-ordinate system, LabelAt(1) gives a declination value that defines a line (of constant declination) along which the numerical right-ascension labels and their associated tick marks will be drawn. Similarly, LabelAt(2) gives the right-ascension value at which the declination labels and ticks will be drawn.

The default bahaviour is for the application to generate its own position for numerical labels and tick marks.

Type:
Floating point.

#### Notes:

• The LabelAt value should use the same units as are used internally for storing co-ordinate values on the appropriate axis. For example, with a celestial co-ordinate system, the LabelAt value should be in radians, not hours or degrees.

• Normally, the LabelAt value also determines where the lines representing co-ordinate axes will be drawn, so that the tick marks will lie on these lines (but also see the DrawAxes  attribute).

• In some circumstances, numerical labels and tick marks are drawn around the edges of the plotting area (see the Labelling  attribute). In this case, the value of the LabelAt attribute is ignored.

#### Description:

This attribute controls the appearance of annotated axes by determining whether the descriptive labels drawn for each axis should include a description of the units being used on the axis. It takes a separate value for each physical axis so that, for instance, the setting "LabelUnits(2)=1"  specifies that a unit description should be included in the label for the second axis.

If the LabelUnits value axis is non-zero, a unit description will be included in the descriptive label for that axis, otherwise it will be omitted. The default behaviour is to include a unit description unless the Frame  being annotated is a SkyFrame  (i.e. a celestial co-ordinate system), in which case it is omitted.

Type:
Integer (boolean).

#### Notes:

• The text used for the unit description is obtained from Unit(axis)  attribute.

• If no axis is specified, (e.g. LabelUnits instead of LabelUnits(2)), then both axes are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining whether the numerical labels for each axis should be drawn upright or not. It takes a separate value for each physical axis so that, for instance, the setting "LabelUp(2)=1"  specifies that numerical labels for the second axis should be drawn upright.

If the LabelUp value axis is non-zero, it causes numerical labels for that axis to be plotted upright (i.e. as normal, horizontal text), otherwise (the default) these labels rotate to follow the axis to which they apply.

Type:
Integer (boolean).

#### Notes:

• In some circumstances, numerical labels and tick marks are drawn around the edges of the plotting area (see the Labelling  attribute). In this case, the value of the LabelUp attribute is ignored.

• If no axis is specified, (e.g. LabelUp instead of LabelUp(2)), then both axes are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining the strategy for placing numerical labels and tick marks.

If the Labelling value is "exterior"  (the default), then numerical labels and their associated tick marks are placed around the edges of the plotting area, if possible. If this is not possible, or if the Labelling  value is "interior", then they are placed along grid lines inside the plotting area.

Type:
String.

#### Notes:

• The LabelAt(axis) attribute may be used to determine the exact placement of labels and tick marks that are drawn inside the plotting area.

#### Description:

This attribute controls the appearance of annotated axes by determining the length of the major tick marks drawn on the axes.

The MajTickLen  value should be given as a fraction of the minimum dimension of the plotting area. Negative values cause major tick marks to be placed on the outside of the corresponding grid line or axis (but subject to any clipping imposed by PGPLOT ), while positive values cause them to be placed on the inside.

The default behaviour depends on whether a co-ordinate grid is drawn inside the plotting area (see the Grid  attribute). If so, the default MajTickLen value is zero (so that major ticks are not drawn), otherwise the default is $+0.015$.

Type:
Floating point.

#### Description:

This attribute controls the appearance of annotated axes by determining the density of minor tick marks which appear between the major axis values. It takes a separate value for each physical axis so that, for instance, the setting "MinTick(2)=2"  specifies the density of minor tick marks along the second axis.

The value supplied should be the number of minor divisions required between each pair of major axis values, this being one more than the number of minor tick marks to be drawn. By default, a value is chosen that depends on the gap between major axis values and the nature of the axis.

Type:
Integer.

#### Notes:

• If no axis is specified, (e.g. MinTick instead of MinTick(2)), then both axes are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining the length of the minor tick marks drawn on the axes.

The MinTickLen  value should be given as a fraction of the minimum dimension of the plotting area. Negative values cause minor tick marks to be placed on the outside of the corresponding grid line or axis (but subject to any clipping imposed by the underlying graphics system), while positive values cause them to be placed on the inside.

The default value is $+0.007$.

Type:
Floating point.

#### Notes:

• The number of minor tick marks drawn is determined by the MinTick(axis) attribute.

#### Description:

This attribute controls the appearance of annotated axes by determining whether labels should be drawn to represent the numerical values along each axis. It takes a separate value for each physical axis so that, for instance, the setting  "NumLab(2)=1"  specifies that numerical labels should be drawn for the second axis.

If the NumLab value for an axis is non-zero (the default), then numerical labels will be drawn for that axis, otherwise they will be omitted.

Type:
Integer (boolean).

#### Notes:

• The drawing of associated descriptive axis labels (describing the quantity being plotted along each axis) is controlled by the TextLab(axis)  attribute.

• If no axis is specified, (e.g. NumLab instead of NumLab(2)), then both axes are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining where numerical axis labels are placed relative to the axes they describe. It takes a separate value for each physical axis so that, for instance, the setting "NumLabGap(2)=-0.01"  specifies where the numerical label for the second axis should be drawn.

For each axis, the NumLabGap value gives the spacing between the axis line (or edge of the plotting area, if appropriate) and the nearest edge of the corresponding numerical axis labels. Positive values cause the descriptive label to be placed on the opposite side of the line to the default tick marks, while negative values cause it to be placed on the same side.

The NumLabGap value should be given as a fraction of the minimum dimension of the plotting area, the default value being $+0.01$.

Type:
Floating point.

#### Notes:

• If no axis is specified, (e.g. NumLabGap instead of NumLabGap(2)), then both axes are affected.

#### Description:

This attribute determines the character size used when drawing each element of graphical output. It takes a separate value for each graphical element so that, for instance, the setting "Size(title)=2.0"  causes the plot title to be drawn using twice the default character size.
Type:
Floating Point.

#### Notes:

• For a list of the graphical elements available, see Section 7.1.

• If no graphical element is specified, (e.g. Size instead of Size(title)), then all graphical elements are affected.

#### Description:

This attribute determines the line style used when drawing each element of graphical output. It takes a separate value for each graphical element so that, for instance, the setting "Style(border)=2"  causes the border to be drawn using line Style 2 (which results in a dashed line).

The range of integer line styles available and their appearance is determined by the PGPLOT graphics system, but includes the following:

(1)
Full line (the default)
(2)
Dashed
(3)
Dot-dash-dot-dash
(4)
Dotted
(5)
Dash-dot-dot-dot

Type:

Integer.

#### Notes:

• For a list of the graphical elements available, see Section 7.1.

• If no graphical element is specified, (e.g. Style instead of Style(border)), then all graphical elements are affected.

#### Description:

This attribute determines the background colour index to use when drawing textual strings - the foreground colour is determined by the Colour(strings)  attribute. Standard X colour names can also be specified, and the nearest colour will be used if the requested colour is not currently in the palette.

If the value "-1" or "clear" is given, the background will be transparent.

Type:
Integer.

#### Description:

This attribute controls the appearance of annotated axes by determining whether textual labels should be drawn to describe the quantity being represented on each axis. It takes a separate value for each physical axis so that, for instance, the setting "TextLab(2)=1"  specifies that descriptive labels should be drawn for the second axis.

If the TextLab value of an axis is non-zero, then descriptive labels will be drawn for that axis, otherwise they will be omitted. The default behaviour is to draw descriptive labels if tick marks and numerical labels are being drawn around the edges of the plotting area (see the Labelling  attribute), but to omit them otherwise.

Type:
Integer (boolean).

#### Notes:

• The text used for the descriptive labels is derived from the Label(axis)  attribute, together with its Unit(axis)  attribute if appropriate (see the LabelUnits(axis)  attribute).

• The drawing of numerical axis labels (which indicate values on the axis) is controlled by the NumLab(axis)  attribute.

• If no axis is specified, (e.g. TextLab instead of TextLab(2)), then both axes are affected.

#### Description:

This attribute controls the appearance of annotated axes by determining where descriptive axis labels are placed relative to the axes they describe. It takes a separate value for each physical axis so that, for instance, the setting "TextLabGap(2)=0.01"  specifies where the descriptive label for the second axis should be drawn.

For each axis, the TextLabGap value gives the spacing between the descriptive label and the edge of a box enclosing all other parts of the annotated grid (excluding other descriptive labels). The gap is measured to the nearest edge of the label (i.e. the top or the bottom). Positive values cause the descriptive label to be placed outside the bounding box, while negative values cause it to be placed inside.

The TextLabGap value should be given as a fraction of the minimum dimension of the plotting area, the default value being $+0.01$.

Type:
Floating point.

#### Notes:

• If drawn, descriptive labels are always placed at the edges of the plotting area, even although the corresponding numerical labels may be drawn along axis lines in the interior of the plotting area (see the Labelling  attribute).

• If no axis is specified, (e.g. TextLabGap instead of TextLabGap(2)), then both axes are affected.

#### Description:

This attribute determines the width of the margin that is cleared around the edges of each drawn text string, in units of the text height. That is, if TEXTMARGIN is set to 0.5, the margin will be half the height of the text. The default is zero.
Type:
Floating point.

#### Description:

This attribute controls the appearance of annotated axes by determining whether tick marks should be drawn on all edges of the plot.

If the TickAll  value is non-zero (the default), then tick marks will be drawn on all edges of the plot. Otherwise, they will be drawn only on those edges where the numerical and descriptive axis labels are drawn (see the Edge(axis)  attribute).

Type:
Integer (boolean).

#### Notes:

• In some circumstances, numerical labels and tick marks are drawn along grid lines inside the plotting area, rather than around its edges (see the Labelling  attribute). In this case, the value of the TickAll attribute is ignored.

#### Description:

This attribute controls the appearance of annotated axes by determining where the title is drawn.

Its value gives the spacing between the bottom edge of the title and the top edge of a bounding box containing all the other parts of the annotated grid. Positive values cause the title to be drawn outside the box, while negative values cause it to be drawn inside.

The TitleGap value should be given as a fraction of the minimum dimension of the plotting area, the default value being $+0.05$.

Type:
Floating point.

#### Notes:

• The text used for the title is obtained from the Title  attribute.

#### Description:

This attribute specifies the plotting tolerance (or resolution) to be used for curves. Smaller values will result in smoother and more accurate curves being drawn (particularly in the presence of discontinuities in the mapping between graphics co-ordinates and physical co-ordinates), but may slow down the plotting process. Conversely, larger values may speed up the plotting process in cases where high resolution is not required.

The Tol value should be given as a fraction of the minimum dimension of the plotting area, and should lie in the range from 1.0E$-$7 to 1.0. By default, a value of 0.001 is used.

Type:
Floating point.

#### Description:

This attribute determines the line width used when drawing each element of graphical output. It takes a separate value for each graphical element so that, for instance, the setting "Width(border)=2.0"  causes the border to be drawn using a line width of 2.0. A value of 1.0 results in a line thickness that is approximately 0.0005 times the length of the diagonal of the entire display surface.
Type:
Floating point.

#### Notes:

• For a list of the graphical elements available, see Section 7.1.

• If no graphical element is specified, (e.g. Width instead of Width(title)), then all graphical elements are affected.