To set the attributes for the chart axes:

chSet 'Axes' 'red,solid,fine'   © or
chSet 'Axes' 1 1 2.5

The mnemonics may be given in any order, or you can use numbers strictly in the sequence shown above (colour, style, weight). The line weights are ‘hair, fine, medium, broad’ or you can give an exact line weight in points. The line styles are ‘solid, dot, dash, ddash, invisible’ or you can use numbers from 1 to 5.

To draw a labelled but invisible axis, it is better to use the ‘invisible’ style as this repositions the labels rather than simply not drawing the axis line and tickmarks.

See also ...
XStyle – X-axis style
YStyle – Y-axis style