First, you need to install Hana Code Insert Plugin.

Once you installed and activated the plugin, visit the Settings => Hana Code Insert option page. Activate the ‘Enable PHP Execution ‘ check box. You need to enable this checkbox to use PHP. Then create an entry by inserting below code This is to show sub page of the current post.

You should not define <?php or ?> and need to enable ‘Evaluate as php code’ when you create the code entry. Please refer to below image for more info.

This function will allow to show the list sub pages. Please note that $post variable has to be defined with ‘global’ modifier. The current post’s ID number is used as one of the function argument.

global $post;
$children = wp_list_pages('title_li=&child_of='.$post->ID.'&echo=0');
if ($children) {
   echo "<ul>$children</ul>";
}

Now once you created the code entry, insert the hana code short code in the parent page.

Then click on the Hana Code Button to insert the code that we just created.

This is the output.

Just like this, you can show the list of categories or sub categories within a post or page.

//Shows full list categories except 10.
echo "<ul>";
wp_list_categories('orderby=name&show_count=1&exclude=10'); 
echo "</ul>";
//Shows the child categories of category 8.
echo "<ul>";
wp_list_categories('orderby=id&show_count=1&use_desc_for_title=0&child_of=8'); 
echo "</ul>";

Category ID or Page ID can be found by inspecting the URL of category or page edit links.

For more informaiton, here are the wordpress reference pages for wp_list_pages and wp_list_categories function.
http://codex.wordpress.org/wp_list_pages
http://codex.wordpress.org/Template_Tags/wp_list_categories

Hana Code Insert Forum

Related posts:

1. Hana Code Insert v2.2