The Token contract is a ERC-20. Each token represents a claim for repayment of 1€ at the end of term and variable return throughout the lifecycle of the security. It is a bearer bond according to the German law, where the token embodies the legal claim against the issuer.
The German Financial Market Authority (BaFin) has fully approved the prospectus which allows for investments starting from 1€. Obviously, that doesn't really make sense on the emission, but each token with a nominal value of 1€ can be traded on secondary markets.
There is a whitelist on the issuance (KYC and AML). On the secondary market, the tokens are unrestricted.
It is simple as that