50 Unidentified 737 orders have been noted on the Boeing Book. I will take a stab at it, and call them China Eastern's Order, in hiding, which was announced by Winging It on July 9, 2015 call out.
"Adding the fifty to last year’s 80 single aisle also confirmed, it brings China Eastern's organization with 130 Boeing single aisle ordered in two years."
I will be excited if Boeing can announce another 50 767 freighters by Fedex before long. By years end, Boeing will have a decent order book comparable to Airbus in some cases and exceeding it on several class types which signal Boeing has come back, making a feisty competitor customers love to do business with.
It’s all “unannounced enigma Customers” making up "The China Syndrome" of Single Aisle !!!