From Linux Man Pages
menu_value - set and get menu item values
SYNOPSIS
#include <menu.h>
int set_item_value(ITEM *item, bool value);
bool item_value(const ITEM *item);
DESCRIPTION
If you turn off the menu option O_ONEVALUE (e.g., with set_menu_opts or menu_opts_off; see opts(3MENU)), the menu
becomes multi-valued; that is, more than one item may simultaneously be selected.
In a multi_valued menu, you can used set_item_value to select the given menu item (second argument TRUE) or dese-
lect it (second argument FALSE).
RETURN VALUE
The function set_item_value returns one of the following:
E_OK The routine succeeded.
E_SYSTEM_ERROR
System error occurred (see errno).
E_REQUEST_DENIED
The menu driver could not process the request.
RELATED
ncurses(3), menu(3MENU).
NOTES
The header file <menu.h> automatically includes the header file <curses.h>.
PORTABILITY
These routines emulate the System V menu library. They were not supported on Version 7 or BSD versions.
menu_value(3MENU)
CATEGORY