Babaoriley: Uninformed question, but can someone explain to me the difference between what is expected be selling in the first quarter of 2019, and the full developement of the transmit engine functionality which, according to the note above, is not expected to be available until sometime later next year?

Not sure whether I understood your question, but here's my answer:

• Early next year: receive optical engine sales
• Later next year: transmit-and-receive optical engine sales