hook_menu wildcard auto-loader for webform submission?
It is looking for a _load() function. In the case of node, user, or taxonomy term arguments (eg %node), it is looking at node_load, user_load, etc.

If you passed %mymodule_foo as the wildcard, then it would look for mymodule_foo_load().

Therefore, if there is a webform submission _load function that loads a submission, thats what you want to use as the wildcard.

The wildcard you want to use is %webform_menu_submission. Webform has a corresponding _load function for it:

/**
 * Menu loader callback. Load a webform submission if the given sid is a valid.
 */
function webform_menu_submission_load($sid, $nid) {
  module_load_include('inc', 'webform', 'includes/webform.submissions');
  $submission = webform_get_submission($nid, $sid);
  return empty($submission) ? FALSE : $submission;
}


Note that this function also needs a $nid argument to work.


  Registered paths may also contain special "auto-loader" wildcard components in the form of '%mymodule_abc', where the '%' part means that this path component is a wildcard, and the 'mymodule_abc' part defines the prefix for a load function, which here would be named mymodule_abc_load(). When a matching path is requested, your load function will receive as its first argument the path component in the position of the wildcard; load functions may also be passed additional arguments


See:


https://stackoverflow.com/a/13788403/295112
https://api.drupal.org/api/drupal/modules!system!system.api.php/function/hook_menu/7.x
http://cgit.drupalcode.org/webform/tree/webform.module#n342