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@@ -530,6 +530,17 @@ FROM extras:${CODE_VERSION}
                      CMD  /code/run-extras
                      ```
                     +To use the default value of an `ARG` declared before the first `FROM` use an
                     +`ARG` instruction without a value:
+                    +
                     +```Dockerfile
                     +ARG  SETTINGS=default
+                    +
                     +FROM busybox
                     +ARG  SETTINGS
+                    +
                     +```
+                    +
                      ## RUN
                      RUN has 2 forms:

Document arg before from