function display_edit_field() {
        global $CFG, $DB, $OUTPUT;

        if (empty($this->field)) {   // No field has been defined yet, try and make one
            $this->define_default_field();
        }
        echo $OUTPUT->box_start('generalbox boxaligncenter boxwidthwide');

        echo '<form id="editfield" action="'.$CFG->wwwroot.'/mod/data/field.php" method="post">'."\n";
        echo '<input type="hidden" name="d" value="'.$this->data->id.'" />'."\n";
        if (empty($this->field->id)) {
            echo '<input type="hidden" name="mode" value="add" />'."\n";
            $savebutton = get_string('add');
        } else {
            echo '<input type="hidden" name="fid" value="'.$this->field->id.'" />'."\n";
            echo '<input type="hidden" name="mode" value="update" />'."\n";
            $savebutton = get_string('savechanges');
        }
        echo '<input type="hidden" name="type" value="'.$this->type.'" />'."\n";
        echo '<input name="sesskey" value="'.sesskey().'" type="hidden" />'."\n";

        echo $OUTPUT->heading($this->name(), 3);

        require_once($CFG->dirroot.'/mod/data/field/'.$this->type.'/mod.html');

        echo '<div class="mdl-align">';
        echo '<input type="submit" class="btn btn-primary" value="'.$savebutton.'" />'."\n";
        echo '<input type="submit" class="btn btn-secondary" name="cancel" value="'.get_string('cancel').'" />'."\n";
        echo '</div>';

        echo '</form>';

        echo $OUTPUT->box_end();
    }