<xsl:if test="some Boolean condition">
  <!-- "if" stuff (there is no "else" here) -->
</xsl:if>

<xsl:choose>
  <xsl:when test="some Boolean condition">
    <!-- "if" stuff -->
  </xsl:when>
  <xsl:otherwise>
    <!-- "else" stuff -->
  </xsl:otherwise>
</xsl:choose>

<xsl:choose>
  <xsl:when test="condition one or condition two">
    <!-- action -->
  </xsl:when>
  <xsl:otherwise>
    <!-- alternative action -->
  </xsl:otherwise>
</xsl:choose>

<xsl:if test="expression">
  ...some output if the expression is true...
</xsl:if>

<xsl:choose>
    <xsl:when test="[conditionOne] or [conditionTwo]">
        <!-- do [action] -->
    </xsl:when>
    <xsl:otherwise>
        <!-- do [alternative action] -->
    </xsl:otherwise>
</xsl:choose>