Blank nested if

Two nested xsl:if instructions state one condition in two places, and the nesting suggests the inner test depends on the outer when both are only conjuncts. One xsl:if joining them with and says it in one place.

Incorrect:

<xsl:if test="$a">
  <xsl:if test="$b">
    <xsl:value-of select="."/>
  </xsl:if>
</xsl:if>

Correct:

<xsl:if test="$a and $b">
  <xsl:value-of select="."/>
</xsl:if>

Only an outer xsl:if holding nothing but the inner one is reported. From XSLT 2.0 on, and may evaluate either operand first, so leave the pair nested when the outer test guards the inner one, as a castable as guards a cast.