How to use Open price to set strike price

How to use today open price to set ATM strike price in formula builder?
By default it takes ATM strike to be what the price is at that time but I want to fix it to day open price.

@Ujjwal can you help with this please?
I am having trouble using OHLC prices in any formula.

I haven’t tried it, but just thinking loudly…you may want to find out (use position) day Open of day and then round it to appropriate level so that you get the strike price.