When you submit the form, the value is presented with debug_dump(), so strings are quoted and array values listed.

: ::
: - Stop the submitted form from bring processed
: - Don't process the form, redirect to another page (e.g. login after session timeout), and remember the values for when they return.

or back to examples 

<?php
	$field = new form_field_time($form, 'Time');
	$field->input_order_set(array('H', 'I', 'S'));
	$field->input_options_value_set('H', range(0, 23));
	$field->input_options_value_set('I', array(0, 15, 30, 45));
	$field->invalid_error_set('Your time does not appear to be correct.');
?>