M3 was an earlier step toward the N3 battleship

What was the M3 design sometimes mentioned alongside G3 and N3?

M3 was an earlier design iteration in the sequence that eventually produced the N3 battleship proposal.

Discussions of the G3 and N3 sometimes introduce an M3 without explaining whether it was a separate class. M3 was one of the earlier design iterations that led toward N3. The letter sequence records the design process rather than three completed ship classes. This clarification helps readers place surviving plans and alternate reconstructions in the correct developmental order.