warning recommended

//(xsl:for-each | xsl:if)[not(* | processing-instruction()) and xslint:normalize-space(.) = "" and not(text()[ancestor::*[@xml:space][1]/@xml:space = 'preserve'])]

Empty content in instructions

An xsl:for-each or xsl:if with no content produces no output, so it is almost certainly a body deleted or never written. Fill it in or remove the element.

Incorrect:

<xsl:for-each select="item">
</xsl:for-each>

Correct:

<xsl:for-each select="item">
  <xsl:value-of select="."/>
</xsl:for-each>

Whitespace and comments count as empty, since a processor ignores them. Under xml:space="preserve" the whitespace is output, and the instruction is left alone.