The default width for bars in an X-bar plot is approximately 3 digits written with the value-tag font. This can be over-ridden to set an exact width, in the scaling units of the X-axis, or the Y-axis for a Gantt chart.

chSet 'bw' 0.4

This allows precise control over bar placement, and could be used (for example) to produce a chart with multiple sets of stacked bars. The function BaasChart in the RainPro workspace illustrates the technique.

You may also pass an array of widths here, for example in a Gantt chart it might be desirable to show some of the bars fatter than others. Normally the array would match the shape of the data, but if necessary it will be reshaped (the elements will be reused cyclically) to match the numbers of items in the data.

chSet 'bw' 2 2 2 3 2

This could also be used in the XBar chart to create proportional bars where the width of the bar varies to show an extra variable.

See also ...
chGantt – project plans
chXbar – bar charts with a defined x-axis