$form->add('text', 'external_identifier', ts('External ID'), $attributes['external_identifier'], FALSE);
$form->addRule('external_identifier',
ts('External ID already exists in Database.'),
$form->add('text', 'external_identifier', ts('External ID'), $attributes['external_identifier'], FALSE);
$form->addRule('external_identifier',
ts('External ID already exists in Database.'),