Rule reminder

'Andare + pp' and 'dovere + essere + pp' both express obligation, but 'andare + pp' is more concise and formal/written. 'Deve essere fatto' (must be done) = 'va fatto'. 'Andare + pp' is preferred in: written regulations, notices, formal instructions, bureaucratic language. 'Dovere + essere + pp' is more common in spoken language. Both are correct, but register matters.