Understanding yamaha part numbers

For a Part Number in the format XXX-XXXXX-XX-XX

XXX-XXXXX-XX-XX 
The first three digits are the Model Code (every model in the Yamaha Product Line has a unique model number) all parts are given a Model Code of the first model they were used on. 

XXX-XXXXX-XX-XX 
The middle five digits are the Basic Code number and indicates the actual part, i.e. 11631 = piston; 11311 = cylinder, etc.
A "W" substituted in the first position of this five-digit group (000-W0000-00-00) indicates a factory assembled kit which differs in content from the original assembly used in production (i.e. 2M0-W0046-00-00 – Rear Break Pad Ass’y). 

XXX-XXXXX-XX-XX 
The next two digits are the Design Code and Design Change digits (so 01 means the part has had one design change). This part may or may notappear different, but it will be interchangeable with the original part. 

XXX-XXXXX-XX-XX 
The last two digits are the Color or Finish Code. 


For a Part Number in the format XXXXX-XXXXX-XX 

All these parts are Hardware (fasteners), they all start with a '9' and end in '00'. 
The second and third digits tells us what type of fastener: 

0 - 'various' 
1 - bolts, cotter pins 
2 - screws, nuts 
3 - oil seals, O-rings, bearings 
4 - spark plugs 
5 - bolts, nuts 
6 - ISO bolts 
7 - ISO screws and nuts 

The fourth and fifth digits tell us what material/surface finish (e.g. chromed). 
Digits six and seven give the diameter (inner or outer) e.g. 08 would be an M8 size. 
Digits eight, nine and ten are the length (except for '901' bolts for some reason) 
There are also standard fastener types...e.g. 

90105-XXXXX are Washer based bolts 
90116-XXXXX are Studs 
90401-XXXXX are Union bolts 
99999-XXXXX means that a part has been superceded by a kit.


Many thanks to;
http://www.benefisca...uk/help.php#q04