Sequence: Alt/Else Block

Conditional branching with `alt` (if) and `else` blocks.

Conditional Block

sequence-alt-else-block.mmd

sequenceDiagram
  participant C as Client
  participant S as Server
  C->>S: Login
  alt Valid credentials
    S-->>C: 200 OK
  else Invalid
    S-->>C: 401 Unauthorized
  else Account locked
    S-->>C: 403 Forbidden
  end

Output

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