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<refentry xmlns=""
version="5.0" xml:id="nominal.image.width">
<refmiscinfo class="other" otherclass="datatype">length</refmiscinfo>
<refpurpose>The nominal image width</refpurpose>
<src:fragment xml:id="nominal.image.width.frag">
<xsl:param name="nominal.image.width" select="6 * $pixels.per.inch"/>
<para>Graphic widths expressed as a percentage are problematic. In the
following discussion, we speak of width and contentwidth, but
the same issues apply to depth and contentdepth.</para>
<para>A width of 50% means "half of the available space for the image."
That's fine. But note that in HTML, this is a dynamic property and
the image size will vary if the browser window is resized.</para>
<para>A contentwidth of 50% means "half of the actual image width".
But what does that mean if the stylesheets cannot assess the image's
actual size? Treating this as a width of 50% is one possibility, but
it produces behavior (dynamic scaling) that seems entirely out of
character with the meaning.</para>
<para>Instead, the stylesheets define a
<parameter>nominal.image.width</parameter> and convert percentages to
actual values based on that nominal size.</para>