Operator 'settings' is called for the show admin pages

You can build a stardard drupal admin settings form. System variables can be set here.

@param $op
@param $arg1

  A drupal admin form

Here a textarea is presented to set the uc_directdebit_account

case 'settings':
$form['uc_directdebit_account'] = array(
'#type' => 'textarea',
'#title' => t('Bank deposit account details'),
'#description' => t('Bank account details for receiving account (eg account name, account number, bank name).'),
'#default_value' => variable_get('uc_directdebit_account', FALSE),
'#rows' => 4,