Magento: Change Category View
To change the category view without having to edit each category individually, use this code in the catalog.xml file to set the page type.
<catalog_category_default translate="label">
<label>Catalog Category (Non-Anchor)</label>
<reference name="root">
<action method="setTemplate"><template>page/1column.phtml</template></action>
</reference>
</catalog_category_default>
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