Help with F23 and F24

Hi.
I''ve managed to get most of the key remaping on tn5250 (in text
mode)... I think the only thing that is missing is F23 (Shift F11) and
F24 (Shift F12)
In my keymap i have made this changes:
 
...
keycode 87 = F11            F23            Console_23
            control     keycode    87 = F11
            alt           keycode    87 = Console_11
            control alt     keycode 87 = Console_11
keycode 88 = F12            F24            Console_24
            control     keycode    88 = F12
            alt           keycode    88 = Console_12
            control alt     keycode 88 = Console_12
...
 
but near the end of the file i have:
 
...
string F20 = "\033[1~"
string Find ... 
...
string Next = "\033[6~"
(Here is the problem i guess)
string F21 = ""
string F22 = "" 
string F23 = "" 
string F24 = "" 
string F25 = "" 
string F26 = ""
 
what are the string values i should place in here?
any advice? how can i guet these codes?
many thanks.