-- Plot option: ylabel [ylabel, <string>] Specifies the <string> that will label the second axis; if this option is not used, that label will be "y", when plotting functions with plot2d or implicit_plot, or the name of the second variable, when plotting surfaces with plot3d or contours with contour_plot, or the second expression in the case of a parametric plot. It can not be used with <set_plot_option>.
There are also some inexact matches for
?? ylabel to see them.
(%o1) true (%i2)