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diff --git a/src/vertical_reference.h b/src/vertical_reference.h
index 8f5d89916d55f8aa4c2cae11b7e996c9ac32aafa..1ac921b45998b5cd400010dec63cefc69473da9a 100644 (file)
--- a/src/vertical_reference.h
+++ b/src/vertical_reference.h
@@ -29,6 +29,9 @@ enum VerticalReference
        TOP_OF_SCREEN,
        CENTRE_OF_SCREEN,
        BOTTOM_OF_SCREEN,
+       /** position on screen is not known, so we are referring
+        *  to the top of the subtitle.
+        */
        TOP_OF_SUBTITLE
 };