7 uses of MENU_IS_ROOT in Drupal 5

menu_edit_item_form in modules/menu/menu.module

Present the menu item editing form.

menu_item_delete_form in modules/menu/menu.module

Menu callback; delete a single custom item.

menu_item_delete_form_submit in modules/menu/menu.module

Process menu delete form submissions.

menu_overview_tree_rows in modules/menu/menu.module

menu_parent_options in modules/menu/menu.module

Return a list of menu items that are valid possible parents for the given menu item. The list excludes the given item and its children.

_menu_build in includes/menu.inc

Build the menu by querying both modules and the database.

_menu_build_visible_tree in includes/menu.inc

Find all visible items in the menu tree, for ease in displaying to user.