XML file question

snippet.xml

<?xml version="1.0"?>
<layout>
    <default>
        <action method="removeItem">
            <type>skin_js</type>
            <name>js/slideshow.js</name>
        </action>
        <action method="addStylesheet">
            <type>skin_css</type>
            <name>css/custom.css</name>
        </action>
    </default>
    <frosit_developer_index_index>
        <reference name="root">
            <action method="setTemplate">
                <template>page/1column.phtml</template>
            </action>
        </reference>
        <reference name="content">
            <block type="core/template" name="frosit.dev.index" template="frosit/placeholder.phtml"/>
        </reference>
    </frosit_developer_index_index>
</layout>