diff --git a/rpi-eeprom-update b/rpi-eeprom-update
index ce607ef..4a78920 100755
--- a/rpi-eeprom-update
+++ b/rpi-eeprom-update
@@ -374,15 +374,27 @@ those devices to stop working until after the system is reboot.
 
 FIRMWARE_RELEASE_STATUS
 
-Specifies the release status of the firmware to apply. The default is 'critical'
-which is the most stable production version. Alternatively, 'stable' or
-'beta' may be selected for development releases.
-A 'critical' update is the latest stable production version and is normally
-only updated after it has been tested via the 'beta' and then a 'stable' release.
+Specifies the release status of the firmware to apply. The default is 'critical'.
+
 Before selecting a firmware release directory this script checks whether there
 is a board revision specific variant e.g. critical-c03111. If present then the
 board-revision specific version is used in preference.
 
+Release status:
+
+critical: The latest production release plus important security or hardware compatibility bug fixes.
+
+stable: Contains new features have already undergone some beta testing.
+These are candidats for new production releases.
+
+beta: New features, bug fixes for development/test purposes. Use at your own
+risk!
+
+As far as rpi-eeprom-update is concerned FIRMWARE_RELEASE_STATUS is just
+the subdirectory mapping under ${FIRMWARE_ROOT}. Therefore, custom release
+directories are supported by creating the relevant directory and changing
+the FIRMWARE_RELEASE_STATUS environment variable.
+
 Examples:
 To extract the configuration file from an EEPROM image:
    rpi-eeprom-config pieeprom.bin --out bootconf.txt