From http://www.w3schools.com (Copyright Refsnes Data)

XSLT <xsl:comment> Element

XSLT Element Reference Complete XSLT Element Reference

Definition and Usage

The <xsl:comment> element is used to create a comment node in the result tree.

Syntax

<xsl:comment>

  <!-- Content:template -->

</xsl:comment>

Attributes

None

Example 1

<xsl:comment>This is a comment!</xsl:comment>

XSLT Element Reference Complete XSLT Element Reference

From http://www.w3schools.com (Copyright Refsnes Data)