The original PDF document is also available for download. This information was up to date as of July 2012.
Y Enterprise/WD RE drive families (4-platter).W Enterprise Advanced Format/WD VelociRaptor.R Enterprise Advanced Format/WD RE drive families.P Mobile Advanced Format/WD Blue WD Green WD Black WD Scorpio.E Mobile/WD Blue WD Green WD Black WD Scorpio®.
B Enterprise/WD RE drive families (3-platter).A Desktop/WD Blue™ WD Green™ WD Black WD Caviar®.H GB/2.5- to 3.5-inch backplane adapter.D TB/2.5- to 3.5-inch backplane adapter.This digit does not translate to additional capacity/LBAs.These drives also use the last digit of the capacity number as a product code (e.g., WD2003FYYS). For 1 TB and larger WD Black™ and enterprise drives, the decimal follows the first digit (e.g., WD1000FYPS is a 1 TB capacity drive).Two, three, or four digits, supports up to 999.9.The base model number is composed of six codes: Medical Equipment (8,623) Ophthalmology and Optic Equipment (1,852) Packing and Packaging Equipment (22,626) Plastic Machinery (14,730) Printing and Graphic Equipment (25,112) Pulp / Paper / Board Machinery (1,098) Ropeways and Mountain Equipment (612) Semiconductor and PCB Manufacturing (10,036) Textile and Leather Machinery (24,690) Various. This is an extract from WD’s own “Model Number Format for OEM and Distribution Channels” document – describing what each letter/number of a WD hard drive model number refers to.