Well, the Item variant is used in all the transaction tables but if you are limiting this for sales or purchase and assuming the user is selecting the variant code you could add some code in those tables in the OnValidate of Variant code.
make use of fieldref and the property relation
Good question, and also good reply to use FieldRef. Another way that will show you some detials is to look at the Field system-table:
There this free app: https://appsource.microsoft.com/en-us/product/dynamics-365-business-central/pubid.insight-works%7caid.d50afbbf-aff3-4dac-bce7-8686b375b994%7cpappid.d50afbbf-aff3-4dac-bce7-8686b375b994?tab=overview
or this one: https://appsource.microsoft…
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