Blank space in my data table - how to name that?

[Tiger1]

I have a table - Location Table. This table has all my companies locations:

Column - key (code given inside companies software per branch i.e. - 59,19,37,etc…
Column - location
Column - Address

My company over the years had errors when entering these [key] branch id’s inside their software and some are blank.

I want to show in my app those [key] branch id’s but i cannot figure out how. They show as blank space in my app - because they were blank in the software. I created the table “location table” to have the key, location and address. I have all keys and locations in it, excpet a blank space. How do i make Appsheets see a blank space in the [key] value?

example:

key = " "
Location = “site error”

Thanks