Each year Shimano prepares the specifications of the parts they will make available to factories that build complete bikes. These specifications are put together in the form of tables, and sent individuals who design bikes and specify the components that will go on them.
Here are the tables of the Shimano line of parts....
Bottom Bracket Specifications
Brake Lever Specifications
Cassette Cog Sets Specifications
Thread-on Freewheel Specifications
Drive Chain Specifications
Crank Sets Specifications
Front Derailleur Specifications
Rear Derailleur Specifications
Rear Freehub Specifications
Front Hub Specifications
SPD Pedal Specifications