i have a code for a field that send a popup message to a user before change a value, the MessageBox is a pop up, take a look on ntd.push
p_web.Script('ntd.push(''MessageBox'','''&p_web.nocolon('Bil3:ShipToZipCode')&''','''&p_web.jsParm(p_web.translate('Confirm'))&''',1,'&Net:LookupRecord&','''',''UpdateBillofLading'','''','''')' )