Hello,
on this beautyful picture taken on March 27th 2007 by Reinhard Dietrich at Pytion station you can see a turkish passenger coach with 11 compartments.
http://en.wikipedia.org/wiki/Istanbul-Pythio_railwayI am no expert in TCDD UIC X coaches, but I am quite sure that it is a Bcm couchette car.
As far as I know, the ordinary Type X 2nd class coaches of TCDD all have 12 compartments. All pictures shown in this thread till now ( which were taken from 1994 to 2000) show these 2nd class coaches.
It seems that in the mid 2000s TCDD used Bcm cars also for the day trains on their European network. In March 2005, I saw myself the morning train form Kapikule formed exclusively of Bcm cars. In the evening, 20 minutes before I left with the Bosfor Espress, the train from Kapikule/Uzunköprü arrived with the car from Pythion attached on the end. I am not sure, but I think this was also a Bcm. I payed more attention to the destination plate on which was written "ISTANBUL - (CH) PITYON - ISTANBUL. I took me then some time to understand that "CH" stands for OSE, not for Switzerland

By the way, at 1:87 Pythion has actually moved to Switzerland - hello Andreas
ACME-model of the Bcm:
All the best,
Stefan