XPath: Expression context - unexpected token here: $p:x2-units-per-pixel

[vnesterovsky]

Error is reported for the following declaration:

<xsl:variable name="right" as="xs:decimal"
  select="$bounds[3] * $p:x2-units-per-pixel"/>

though

<xsl:variable name="right" as="xs:decimal"
  select="$p:x2-units-per-pixel"/>

is OK for the plugin.