I've been experimenting with PDI lately and now I'm loading some dimensions with SCD type 2. So I decided to use the Dimension lookup/update step. But there's something that confused me a bit: the version field. I don't understand why it's required, since the start and end dates already serve the purpose of versioning a business key.

I had to create an additional field in my dimensions just because of that, and I probably won't need it. So, why is it required?