This file contains information about the theme. It is used during installation and also during configuration of the theme. To create a new theme.xml file or derive one from an existing v1.x theme.php file use the conversion tool here: yoursite.com/e107_admin/theme.php?mode=convert Example from the bootstrap theme:

<?xml version="1.0" encoding="utf-8"??>
<e107theme compatibility="2.0" date="2012-12-01" name="bootstrap" version="1.0">
    <author email="@" name="e107 Inc" url="http://e107.org"></author>
    <summary>Bootstrap e107 admin theme</summary>
    <description>Bootstrap e107 admin theme</description>
    <category>generic</category>
    <keywords>
        <word>bootstrap</word>
        <word>clean</word>
    </keywords>
    <screenshots>
        <image>preview.jpg</image>
        <image>fullpreview.jpg</image>
    </screenshots>
    <stylesheets>
        <css file="style.css" name="Default"></css>
        <css file="css/superhero.css" name="Superhero"></css>
    </stylesheets>
    <layouts>

        <layout default="true" name="default" title="Default"></layout>
        <layout name="default-home" title="Default Home">
            <custompages>FRONTPAGE</custompages>	
        </layout>
        <layout name="hero" title="Hero"></layout>
        <layout name="marketing-narrow" title="Marketing Narrow"></layout>
        <layout name="docs" title="Documentation"></layout>
    </layouts>
</e107theme>

Tip: If you are developing a commercial theme, you'll want to add a few extra attributes so that it displays correctly in the admin area under "Find Themes". .

<e107theme ...="" currency="EUR" name="bootstrap" price="25.00" url="http://direct-path-to-my-theme-purchase-page.com"></e107theme>

Just package your theme's zip file with only the theme.xml and any images (including screenshots) , excluding .php, .css files etc. before sharing it. When the user clicks to download the theme, it will display the url you have provided.