Dotted Line Chart

Yes it is possible, you need to modify the brush. Let me know if you need more information on it, but you need to set the line stroke.

Short answer:

<param name="charting.lineBrush">dashedStroke</param>

Here's the link: Brush Strokes

Long Answer:

I like to establish a core brush I use on a chart when I make modifications, in this case, a dashed line brush:

<param name="charting.myBrush">dashedStroke</param>
<param name="charting.myBrush.dashSize">10</param>
<param name="charting.myBrush.dashSpacing">10</param>
<param name="charting.myBrush.color">0xFF0000</param>
<param name="charting.myBrush.thickness">5</param>

Basically, this will create one super ugly thick red dashed line. When dealing with charts, you need to tell splunk how to reference the "series" of data (incase there is more then one line).

<param name="charting.myBrushPalette">list</param>
<param name="charting.myBrushPalette.brushes">[@myBrush]</param>
<param name="charting.chart.lineBrushPalette">@myBrushPalette</param>

We are telling splunk to now use a "list" for the series. This list only contains 1 option, therefore it's used for each line on the chart. You can specify additional brushes for line rendering other lines by following the same process.

<param name="charting.myBrush">dashedStroke</param>
<param name="charting.myBrush.dashSize">10</param>
<param name="charting.myBrush.dashSpacing">10</param>
<param name="charting.myBrush.color">0xFF0000</param>
<param name="charting.myBrush.thickness">5</param>
<param name="charting.myBrush2">solidStroke</param>
<param name="charting.myBrush2.color">0x00FF00</param>
<param name="charting.myBrushPalette">list</param>
<param name="charting.myBrushPalette.brushes">[@myBrush,@myBrush2]</param>
<param name="charting.chart.lineBrushPalette">@myBrushPalette</param>

This will use the dotted line for the "first" series, and a green line for the "second" series, reguardless of name. If you want more control, use the "field" palette to define the name of the series to reference a brush.

<param name="charting.myBrush">dashedStroke</param>
<param name="charting.myBrush.dashSize">10</param>
<param name="charting.myBrush.dashSpacing">10</param>
<param name="charting.myBrush.color">0xFF0000</param>
<param name="charting.myBrush.thickness">5</param>
<param name="charting.myBrush2">solidStroke</param>
<param name="charting.myBrush2.color">0x00FF00</param>
<param name="charting.myBrushPalette">field</param>
<param name="charting.myBrushPalette.fieldBrushes">{Average_Duration:@myBrush,Count:@myBrush2}</param>
<param name="charting.myBrushPalette.defaultBrushPalette">@myBrush2</param>
<param name="charting.chart.lineBrushPalette">@myBrushPalette</param>

This will establish the "count" line as the dotted line, the "Average_Duration" line as the green line, then make any other line the same green line as "Average_Duration".