Events are classified under different Project Types. Give each project type a code that corresponds to the accounting code of different projects. For example, you can generate overviews per type of project via Reports. It is a categorization that is only visible to your Backstage users, not to your website or ticketshop visitors.

You assign the project type at Events - Main. This way you can quickly see what kind of event it is.

You create project types yourself via Settings - Planning - Project types.