[Ln,Cp] = grfun.vline(Xpos,...)
[Ln,Cp] = grfun.vline(Ax,XPos,...)
'XPos' [ numeric ] - Horizontal position or vector of positions at which the vertical line or lines will be drawn.
Ax [ numeric ] - Handle to an axes object (graph) or to a figure window in which the the line will be added; if not specified the line will be added to the current axes.
Ln [ numeric ] - Handle to the vline(s) plotted (line objects).
Cp [ numeric ] - Handle to the caption(s) created (text objects).
'caption=' [ char ] - Annotate vline with a text string.
'excludeFromLegend=' [ true | false ] - Exclude vline from legend.
'hPosition=' [ 'center' | 'left' | 'right' ] - Horizontal position of the caption.
'vPosition=' [ 'bottom' | 'middle' | 'top' | numeric ] - Vertical position of the caption.
'timePosition=' [ 'after' | 'before' | 'middle' ] - Placement of the vertical line on the time axis: in the middle of the specified period, immediately before it (between the specified period and the previous one), or immediately after it (between the specified period and the next one).