What do you for zero quantity on multi configuration BOMs?

This is more of a general poll, I guess. What does your company use for items on a multi-configuration BOM with zero quantity? Do you use a - (dash), leave it blank or use 0 (zero) quantity? I've always used a - (dash) at my previous companies, but on our old Creo drawings here, they are set to being blank. I'm curious as to what others are using. I couldn't find anything in any ASME standard regarding this so I guess it's up to the company. I'm creating SW templates and have it set to - (dash).

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