> With the imperial / metric versions. the only thing I can think of is that > it may be that because kicad (at least the 2009 versions) use imperial as > it's base measurement system that someone created the imperial versions to > avoid grid mismatches.
That's not the reason, with its 1/10mil resolution pcbnew has no problem handling metric modules (well, maybe until you need chip bonding, at least :D) The metric/imperial usage with passives is mostly a cultural one in the industry and varies from country to country... For example, here in Italy when we talk about common capacitor/resistors we usually use the imperial units (0603 being the most common AMT). Tantalium are referred as metric (or with case letter coding) and for inductors... well, smaller one are imperial but bigger one are referred as metric... also electrolytic are referred using the panasonic case names and tank/choke inductors using the S/M/L/XL size from wurth! So, at the end, everyone make its own standard... The IPC standard naming is IMHO unwieldy, too complex to use in the usual cases! (and, anyway, remember that there are around a dozen or so of SOT-23 variants, too!)
