Semaphore signal for "Shift to numeric."  Applies to the signals immediately following.
A → 1, B → 2, C → 3, D → 4, E → 5, F → 6, G → 7, H → 8, I → 9, K → 0
If a J is sent after the numeric signal, it means to shift to alphabetic.

Based on the diagrams at http://www.anbg.gov.au/flags/semaphore.html
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