install.rdf

<?xml version="1.0"?>

<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:em="http://www.mozilla.org/2004/em-rdf#">

  <Description about="urn:mozilla:install-manifest">
    <em:id>{a0faa0a4-f1a7-4098-9a74-21efc3a92372}</em:id>
    <em:version>45.0.0</em:version>
    <em:type>2</em:type>
    
    <!-- Target Application this extension can install into, 
        with minimum and maximum supported versions. --> 
    <!-- Firefox -->
    <em:targetApplication>
     <Description>
       <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
       <em:minVersion>43.*</em:minVersion>
       <em:maxVersion>45.*</em:maxVersion>
     </Description>
    </em:targetApplication>

    <!-- Thunderbird -->
    <em:targetApplication>
     <Description>
       <em:id>{3550f703-e582-4d05-9a08-453d09bdfdc6}</em:id>
       <em:minVersion>1.5</em:minVersion>
       <em:maxVersion>24.*</em:maxVersion>
     </Description>
    </em:targetApplication>
    
    <!-- Front End MetaData -->
    <em:name>DictionarySearch</em:name>
    <em:description>Looks up selected word in an online dictionary</em:description>
    <em:creator>Jaap Haitsma</em:creator>
    <em:homepageURL>http://dictionarysearch.mozdev.org/</em:homepageURL>

    <!-- Front End Integration Hooks (used by Extension Manager)-->
    <em:optionsURL>chrome://dictionarysearch/content/dictionarysearchPrefDialog.xul</em:optionsURL>    
    <em:iconURL>chrome://dictionarysearch/skin/dictionarysearch.png</em:iconURL>
  </Description>      
</RDF>