Re: Nodes get new IDs in function?

<xsl:function name="o2e:parent-heading" as="element()*">
     <xsl:param name="heading" as="element()"/>
     <xsl:copy-of select="$heading/preceding-sibling::h:*[self::h:h1 or
self::h:h2 or self::h:h3 or self::h:h4 or self::h:h5 or
self::h:h6][o2e:heading-level(.)&lt;
o2e:heading-level($heading)][1]"/>
</xsl:function>

The problem is, it seems that nodes returned from the parent-heading()
function get different IDs than identical nodes in the source
document. Is this the specified behavior, i.e. functions construct new
nodes, which get new IDs?