German freelancer without business registration – acceptable document for Artifact Signing organization validation?

Hello,

I am a self-employed freelancer (“Freiberufler”) in Germany. I am not incorporated and do not have a trade registration (“Gewerbeanmeldung”), because my freelance activity is registered directly with the German tax office.

My Artifact Signing organization validation is currently requesting official business registration documentation. I can provide an official document from the German tax office showing my legal name, address and German tax number. However, this document normally has no expiration date.

The organization name currently entered in the validation request is “Alva Code”. This is my product/brand name, not a separate legal entity. My official documents show my full legal name instead.

Before using one of the three document-upload attempts, could you please confirm:

1. Is an official tax registration letter or a recent certificate from the German tax office acceptable for a German freelancer?
2. Should I delete this validation request and create a new organization validation using my full legal name instead of “Alva Code”?
3. Is a German tax number acceptable as the Business Identifier?
4. How should I handle an official document that has an issue date but no expiration date? Thank you.