`UNICODEMAP_ENABLE`
-This allows you to send Unicode characters using `X(<map index>)` in your keymap. You will need to maintain a mapping table in your keymap file. All possible code points (up to `0x10FFFF`) are supported.
+This allows you to send Unicode characters using `X(<map index>)` in your keymap. You will need to maintain a mapping table in your keymap file. All possible code points (up to `0x10FFFF`) are supported.
`UCIS_ENABLE`
This enables split keyboard support (dual MCU like the let's split and bakingpy's boards) and includes all necessary files located at quantum/split_common
+`SPLIT_TRANSPORT`
+
+As there is no standard split communication driver for ARM-based split keyboards yet, `SPLIT_TRANSPORT = custom` must be used for these. It will prevent the standard split keyboard communication code (which is AVR-specific) from being included, allowing a custom implementation to be used.
+
+`CUSTOM_MATRIX`
+
+Lets you replace the default matrix scanning routine with your own code. You will need to provide your own implementations of matrix_init() and matrix_scan().
+
+`DEBOUNCE_TYPE`
+
+Lets you replace the default key debouncing routine with an alternative one. If `custom` you will need to provide your own implementation.
+
## Customizing Makefile Options on a Per-Keymap Basis
If your keymap directory has a file called `rules.mk` any options you set in that file will take precedence over other `rules.mk` options for your particular keyboard.