According to the following document, “the model number suffix (characters to the right of the dash following the model number) is only for in-house use. Refer to Change Administration’s Model Specification (document number 2096-000101).”
Model Number Format for OEM and Distribution Channels:
http://www.wdc.com/wdproducts/library/Flyer/ENG/2579-001028.pdf
I haven’t seen WD’s internal document, but here is an explanation in Russian:
http://www.acelab.ru/dep.pc/doc.pc3000dos/060713.001/WD-main-N-2.pdf
Here is Google’s English translation:
http://translate.google.com/translate?hl=en&ie=UTF8&prev=_t&sl=ru&tl=en&u=http://www.acelab.ru/dep.pc/doc.pc3000dos/060713.001/WD-main-N-2.pdf
