Updated FAQ Keymap (markdown)

FAQ-Keymap.md

@@ -112,3 +112,12 @@ https://github.com/tekezo/Karabiner/issues/403
 
 ## Esc and `~ on a key
 https://github.com/p3lim/keyboard_firmware/commit/fd799c12b69a5ab5addd1d4c03380a1b8ef8e9dc
+
+
+## 32 Fn keys are not enough?
+### actionmap
+It uses 16 bit codes and no limitation of 32 Fn at the expense of memory space. TMK keymap is actually is 8 bit codes as subset of the actionmap.
+https://github.com/tmk/tmk_keyboard/issues?utf8=%E2%9C%93&q=is%3Aissue+actionmap
+
+### extension for modified keys
+https://geekhack.org/index.php?topic=41989.msg1885526#msg1885526