Question

Using c#3 compiled transforms the following seems to work just fine…

<xsl:choose>
    <xsl:when test="$valA > $valB">
        <xsl:value-of select="$maxUnder" />
    </xsl:when>
    <xsl:when test="$valA &lt; $valC">
        <xsl:value-of select="$maxOver" />
    </xsl:when>
</xsl:choose>

However if i dare use a < in place of < it gives an error…

<xsl:choose>
    <xsl:when test="$valA > $valB">
        <xsl:value-of select="$maxUnder" />
    </xsl:when>
    <xsl:when test="$valA < $valC">
        <xsl:value-of select="$maxOver" />
    </xsl:when>
</xsl:choose>

System.Xml.XmlException: ‘<‘,
hexadecimal value 0x3C, is an invalid
attribute character.

So why is > ok and not < ?

Answer 1

Because > isn’t a reserved character in XML, but < is.

From section 2.4 of the XML 1.0 spec (5th edition):

The ampersand character (&) and the
left angle bracket (<) must not appear
in their literal form, except when
used as markup delimiters, or within a
comment, a processing instruction, or
a CDATA section. If they are needed
elsewhere, they must be escaped using
either numeric character references or
the strings “&” and “<”
respectively. The right angle bracket
(>) may be represented using the
string “>“, and must, for
compatibility, be escaped using either
“>” or a character reference when
it appears in the string “]]>” in
content, when that string is not
marking the end of a CDATA section.