Previous close
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A picture says more...
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Condition.jpg -
For condition do as follows.

Candle ID will specify which candle you are referring to.......
co.jpg -
Thanks. That was easier than I thought. Thanks again

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If needed, "Once per bar" block can be used. It matter if it is located before or after the condition. In one case you have "Once per bar check that condition" and in the other you have "Check that condition (on every tick) and if it is true then once per bar do the next things".