region.inner.extent length region.inner.extent Specifies the width of the inner side region 0in The region inner extent is the width of the optional text area next to the inner side (binding side) of the body region. For double-sided output, this side region is fo:region-start on a odd-numbered page, and fo:region-end on an even-numbered page. For single-sided output, this side region is fo:region-start for all pages. This correspondence applies to all languages, both left-to-right and right-to-left writing modes. The default value of this parameter is zero. If you enlarge this extent, be sure to also enlarge the body.margin.inner parameter to make room for its content, otherwise any text in the side region may overlap with the body text. See also region.outer.extent, body.margin.inner, body.margin.outer, side.region.precedence.