DefaultDataWithAccess.php
<form item="Blog" target="/blog/{title}/" access="call:allow_edit_blog">
<on s=403>Access denied</on>
<p-data type="default">
</p-data>
<input type="text" name="title" maxlength="75">
<textarea name="body" maxlength="2000" minlength="50"></textarea>
</form>