I don't think that's a great comparison. Exons already have sequences that mark 'block' boundaries; amino acids are encoded in triplets of base pairs, but sort

I don't think that's a great comparison. Exons already have sequences that mark 'block' boundaries; amino acids are encoded in triplets of base pairs, but sort of like you see in 8b/10b encoding, there are sequences that are valid but only used for control purposes and don't correspond to amino acids.