diff --git a/src/uas_standards/astm/f3411/v22a/constants.py b/src/uas_standards/astm/f3411/v22a/constants.py
index dc7a4ac..d2b9567 100644
--- a/src/uas_standards/astm/f3411/v22a/constants.py
+++ b/src/uas_standards/astm/f3411/v22a/constants.py
@@ -36,5 +36,5 @@ class Scope(str, Enum):
 SpecialHeight = -1000
 MinTrackDirection = -359
 MaxTrackDirection = 359
-SpecialTrackDirection = 361
+SpecialTrackDirection = 361 # Invalid, No Value or Unknown
 MinTrackDirectionResolution = 1
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