When do we speak of an open-air assembly or procession?

In principle, the definition of the Federal Constitutional Court can be used as a guide:

"An assembly within the meaning of Article 8 (1) of the Basic Law exists when several persons meet locally for a communal discussion or demonstration aimed at participating in the formation of public opinion." This definition should not deter you. If you want to exercise your fundamental right and take a stand on an issue in this way, for example, you can register an assembly/parade with or without a march with the city of Wolfsburg as the assembly authority.