3 calls to form_options_flatten()

node_filter_form_submit in modules/node/node.admin.inc
Form submission handler for node_filter_form().
user_filter_form_submit in modules/user/user.admin.inc
Process result from user administration filter form.
_form_validate in includes/form.inc
Performs validation on form elements.

Buggy or inaccurate documentation? Please file an issue. Need support? Need help programming? Connect with the Drupal community.