Futures Symbols WebTrader vs Strategy Page

I have noticed that if I check positions in the webtrader the symbol is slightly different for futures there vs on the main strategy page. See below how @VXH21 = @VXH1. Can someone explain the difference for me? I am working on an API order entry system and just need to know what to expect.

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If you are asking what to use when sending trades to C2, you can always use the one-digit year codes.
(@VXH1)

Thank you! That works great.