Why does NemID display "Pseudonym" instead of name in signature?

Question:

Why does NemID display “Pseudonym” instead of name in signature?

Answer:

If an NemID certificate is set to use “pseudonym” instead of the user’s name, it is because user has chosen to hide his / her name. This can be done by users at www.nemid.nu

Question:

Will that still be a valid signature? If not, how can I detect it before it goes its rounds in our systems?

Answer:

It’s still a valid AES (Advanced Electronic Signature) in eIDAS terms, which is what is valid in Denmark, as long as it’s clearly marked that the name is a pseudonym and not simply a false name. The resulting signature will still contain the user’s PID number (and CPR number, if configured), so that the signer can be uniquely identified. So yes, the signature is legally valid.

You might want to treat these signatures as special cases for your business processes, however. There is only one way to do this, unfortunately, and that is to see if the signer’s name exactly matches the string “Pseudonym”.