I understand how XPath syntax works, and can write Xpath commands to extract certain information from a XML file.  

I would like to convert my XPath commands to XSLT scripts so that someone else can just run the script over the XML file to get the same output. 

e.g. 

I have a XML file that, let's say, looks like follows:

```
<?xml version="1.0" encoding="UTF-8"?>
  <library>
        <section id="109196796">
            <master_information>
                <shelf_identifier>
                    <identifier type="CodeX" type_id="2">LB1500605917</identifier>
                    <identifier type="Common Code" type_id="15">150060591</identifier>
                </shelf_identifier>
                <shelf_master>
                    <section_type>1</section_type>
                    <book_type>3</book_type>
                </shelf_master>
            </master_information>
        </section>
        <section id="109196798">
            <master_information>
                <shelf_identifier>
                    <identifier type="CodeX" type_id="2">LB0777775917</identifier>
                    <identifier type="Common Code" type_id="15">077777591</identifier>
                </shelf_identifier>
                <shelf_master>
                    <section_type>1</section_type>
                    <book_type>3</book_type>
                </shelf_master>
            </master_information>
        </section>
        <section id="109196800">
            <master_information>
                <shelf_identifier>
                    <identifier type="CodeX" type_id="2">LB2589165917</identifier>
                    <identifier type="Common Code" type_id="15">258916591</identifier>
                </shelf_identifier>
                <shelf_master>
                    <section_type>1</section_type>
                    <book_type>3</book_type>
                </shelf_master>
            </master_information>
        </section>
  </library>

```

If I run the XPath command below,

```
//identifier[@type='CodeX']

```

I get the output:

```
LB1500605917
LB0777775917
LB2589165917

```

..which is expected. Now, I tried converting the XPath command to an XSL syntax as below:

```
<?xml version="1.0" encoding="ISO-8859-1"?>

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="text"/>
    <xsl:variable name="return">
    <xsl:text>
</xsl:text> <!-- defined a line break -->
    </xsl:variable>
    <xsl:template match="//library"></xsl:template>
    <xsl:template match="//section/master_information/shelf_identifier/identifier"> 
        <xsl:value-of select="@type='CodeX'"/>
        <xsl:value-of select="$return"/> <!-- this basically puts a line break -->
    </xsl:template>
</xsl:stylesheet>

```

The XSL seems to be correct. However, no output is generated. 

I am new to XSL/XSLT. What am I doing wrong?