Refers to: How to add an image wrapped in a link to the image so that end users may select the image.

I am attempting to make it possible for a user to fill in a link and image by selecting an image from media in his content tab for the page.

I have the following macro:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE xsl:Stylesheet [ <!ENTITY nbsp "&#x00A0;"> ]>
<xsl:stylesheet
    version="1.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:msxml="urn:schemas-microsoft-com:xslt"
    xmlns:umbraco.library="urn:umbraco.library"
    exclude-result-prefixes="msxml umbraco.library">

  <xsl:output method="xml" omit-xml-declaration="yes"/>

  <xsl:param name="currentPage"/>
  <xsl:param name="galleryName" />
  
  <xsl:template match="/"> 
    <xsl:variable name="media" select="umbraco.library:GetMedia($currentPage/imageAlias, 0)" />
    <a ref="{$galleryName}" href="{$media/umbracoFile}">
      <img src="{$media/umbracoFile}" alt="{$media/altText}" />
    </a>
  </xsl:template>
</xsl:stylesheet>

How do I get this macro into my document type so that I can fill it out on the content tab for the pages?

I understand how macros work with templates, but I will not be allowing the user access to the templates section to fill out macros there, and the template is used in more than one place, so the content on each one has to be different, and I shouldn't have to have 2 templates to do that.

Should this be a Data Type instead of a Macro?  What are the steps in creating a data type if that is what is required here?

Thanks for your time,