if (!defined ('TYPO3_MODE'))     die ('Access denied.');

$TCA["extensionkey"] = array (
...
    "types" => array (
        "0" => array("showitem" => "--div--;Tab 1,sys_language_uid;;;;1-1-1, l18n_parent, l18n_diffsource, hidden;;1, eventdate, category, title;;;;2-2-2, subtitle;;;;3-3-3, shorttext,--div--;Tab 2, bodytext;;;richtext[cut|copy|paste|...")
    ),
...