So this was Ruler line

One can also fix the Length of Ruler line with WIDTH parameter

So This was 150 point Horizontal Ruler line

Yes! by default it takes CENTER alignment, We can change even this to LEFT or RIGHT or CENTER

following are the examples

So this is left Aligned Horizontal Ruler

this is CENTER Aligned Horizontal Ruler

this is RIGHT Aligned Horizontal Ruler with 50% percentage WIDTH parameter

by specifying SIZE of ruler one can increase Thickness of line

And by putting NOSHADOW it gives shadowless ruler