A question about the 'Epochs and the Sequencing Window' section in the overview.md of specs

[Nickqiaoo]

The diagram describes how L2 blocks are derived from L1 blocks.I am puzzled about B1 in the diagram. Does 'B1' here stand for batch data? It seems in the diagram that the L1 origin of the L2 block includes the batch data for this epoch.Does The L1 origin should never contain any data needed to construct sequencer batches of its epoch？

[smartcontracts]

cc @protolambda

[protolambda]

I believe D is deposits, and B is batches. Deposits come at the same time as that the L1 origin is recognized in the L2 chain. This always happens before the resulting L2 block is batch-submitted to the L1. The batch-data then allows other nodes to reconstruct the exact same L2 block.

[Nickqiaoo]

I believe D is deposits, and B is batches. Deposits come at the same time as that the L1 origin is recognized in the L2 chain. This always happens before the resulting L2 block is batch-submitted to the L1. The batch-data then allows other nodes to reconstruct the exact same L2 block.

My confusion is whether B1 is the batches generated in Epoch1. If so, it shouldn't be submitted in the block of L1 Epoch1, because by the time the first L2 block of Epoch1 is generated, the corresponding L1 origin, which is the block of L1 Epoch1, has already been generated. B1 should be submitted in the blocks of the subsequent sequencing window size, just like B2 B3 in the diagram.