Do all index shift components (within the same cluster range) work together? Is there an industry standard that is adhered to? For instance, on a 7 cog rear system, is the total cable take-up, and allocation between any two gears the same with all major brands? In other words, are the detents in the shifter for each gear uniformly spaced from one unit to another (brand or model), and will they work with all dérailleurs?

I realize that there are differences when you talk about different number of cogs. Spacing is tighter on newer high count systems (after 8 or 9 rear gears)? What about older 5, 6 & 7 gear systems? Is there a 'compatibility chart' anywhere?

If you read the microtype white sheets that come with some items, you would think that you cannot mix components, yet many bicycles do indeed come with say SRAM shifters and Shimano dérailleurs.