<varlistentry id="options.ViewportX">
      <term>ViewportX <emphasis remap='I'>number</emphasis></term>
      <listitem>
<para>Specifies the coordinate along the x-axis that <command>afterstep</command> should
place a window.  This allows opening a window on a particular desk and view.
<emphasis remap='I'>number</emphasis> is measured in pixels and the screen resolution is the outline
of a desk's particular boundaries; where it will then place it upon another
desk or view.  Combined with <emphasis remap='I'>ViewportY</emphasis>, a window can be given geometry
by <command>afterstep</command> and be placed in the desired desktop and view.</para>
      </listitem>
</varlistentry>
