nlobjForm.addSubTab ( name , label , tab )

/**
* add a subtab (nlobjTab) to this form and return it.
*
* @param {string} name subtab name
* @param {string} label subtab label
* @param {string} [tab] parent tab that this subtab lives on. If empty, it is added to the main tab.
* @return {nlobjTab}
*
* @since 2008.2
*/