# `semantic.principal_variant_required`

Principal declares neither a user nor a service.

Area 8, [Identity](../topics/identity.md); not declinable; the next step is usually the agent's.

```jadpo
principal {}
```

```text
error: The principal declares no kind of caller
 --> main.jadpo:1:1
  |
1 | principal {}
  | ^^^^^^^^^ no `user:` or `service:`
  reason: A principal says which entity a signed-in caller is: `user:` for a person, `service:` for another system, or both.
  next: Add `user: { subject: <Entity>.<field> }` (agent)
  rule: semantic.principal_variant_required
  help: https://jadpo.dev/docs/errors/semantic.principal_variant_required

check failed: 1 error, 1 file
```