Definition

An XSL Transform is a document utilizing XSLT which gives you the ability to transform XML documents into other formats such as HTML, plain text, or even a different XML structure. Transforms are extremely useful for restructuring data into a new format or serialization.

Creating an XSL Transform

To create a transform click the "Create" button and select "Transform". 

Here you are presented with a text editor into which you can type your transform.

Click "Create" and your Transform will be saved. You can go back at any point to Edit the Transform by selecting the "Edit" tab. 

Sample XSL Transform

Step 1 - Obtain original XML document


<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="example.xsl"?>
<Article>
  <Title>My Article</Title>
  <Authors>
    <Author>Mr. Foo</Author>
    <Author>Mr. Bar</Author>
  </Authors>
  <Body>This is my article text.</Body>
</Article>

Step 2 - Write XSL Transform


<?xml version="1.0"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

  <xsl:output method="text"/>

  <xsl:template match="/">
    Article - <xsl:value-of select="/Article/Title"/>
    Authors: <xsl:apply-templates select="/Article/Authors/Author"/>
  </xsl:template>

  <xsl:template match="Author">
    - <xsl:value-of select="." />
  </xsl:template>

</xsl:stylesheet>

This Transform capatures the title of the article and prints it out prepended with "Article - " by accessing the value located within the <title> tag using select="/Article/Title/". The same mechanism is used to access the authors of the article except since there are multiple values instead of simply obtaining the raw value it is passed along to a template for printing, as can be seen on the line showing <xsl:template match="Author">.

Step 3 - Output document


Article - My Article
Authors:
- Mr. Foo
- Mr. Bar

This is obviously a very simple example but you can use these principles to start transforming your data however is necessary.

Example source: https://developer.mozilla.org/en-US/docs/XSLT_in_Gecko/Basic_Example