diff --git a/_version.py b/_version.py
index a9bc3f9..db68c9d 100644
--- a/_version.py
+++ b/_version.py
@@ -20,12 +20,18 @@
 _cFS_GrndSys_build_number = 12
 _cFS_GrndSys_build_baseline = "v3.0.0-rc4"
 
-# Version Number Definitions
-# ONLY APPLY for OFFICIAL release builds
-_cFS_GrndSys_MAJOR = 2
-_cFS_GrndSys_MINOR = 1
-_cFS_GrndSys_REVISION = 0
-_cFS_GrndSys_MISSIONREV = 255
+# Version Number Definitions see doxygen docs for definitions
+_cFS_GrndSys_MAJOR = 2 # Major version number 
+_cFS_GrndSys_MINOR = 1 # Minor version number 
+_cFS_GrndSys_REVISION = 0 # Revision version number 
+
+
+# Mission revision.
+# 
+# Reserved for mission use to denote patches/customizations as needed.
+# Values 1-254 are reserved for mission use to denote patches/customizations as # needed. NOTE: Reserving 0 and 0xFF for cFS open-source development use 
+# (pending resolution of nasa/cFS#440)
+_cFS_GrndSys_MISSIONREV = 255 
 
 # Development Build format for __version__
 # Baseline git tag + Number of commits since baseline