How to check field exists or not in eText Template

Friends,

If you have any idea on how to check whether an element (XML Tag / Field) exists in the file or not in eText template then, please share your input. Ex. I want to check element User_Role exist or not .. If exist then I need to check User_Role="Line Manager".

in RTF we can do something like below

<?if:element_name!=?>

<?if:element_name and element_name="?>

<?if:not(element_name)?>

How the same can be done in eText Template?

Regards,

Mano