Magento 2.3 what is "Empty attribute value constant' in import

Question

Is anyone know in Mageno 2.3 product import a new field is introduced i.e "Empty attribute value constant" field. What is the use for

Answer 1

When updating existing (not adding new) products this is where you define the constant that if found in your CSV will empty the existing attribute value. Previously if a product has an attribute that has a value already set and you imported an empty string because the value needs to be emptied, the attribute was not overwritten with the empty string and the old value remained.

This bug was fixed and the imported updated so you can explicitly state when an attribute should be wiped by specifying the value to look for in the CSV.

https://github.com/magento/magento2/issues/7468