# Batch Submitter The batch submitter, also referred to as the batcher, is the entity submitting the L2 sequencer data to L1, to make it available for verifiers. [derivation spec]: derivation.md The format of the data transactions is defined in the [derivation spec]: the data is constructed from L2 blocks in the reverse order as it is derived from data into L2 blocks. The timing, operation and transaction signing is implementation-specific: any data can be submitted at any time, but only the data that matches the [derivation spec] rules will be valid from the verifier perspective. The most minimal batcher implementation can be defined as a loop of the following operations: 1. See if the `unsafe` L2 block number is past the `safe` block number: `unsafe` data needs to be submitted. 2. Iterate over all unsafe L2 blocks, skip any that were previously submitted. 3. Open a channel, buffer all the L2 block data to be submitted, while applying the encoding and compression as defined in the [derivation spec]. 4. Pull frames from the channel to fill data transactions with, until the channel is empty. 5. Submit the data transactions to L1 The L2 view of safe/unsafe does not instantly update after data is submitted, nor when it gets confirmed on L1, so special care may have to be taken to not duplicate data submissions.