e card
sales.  But it turns out that, behind the design room door, these
shops are all violating one another's patents, sometimes knowingly and
sometimes accidentally.  The patents are so unpredictable and so
potentially broad that no card manufacturer can ever be certain it's
safe, even after doing a patent search.  Thus, manufacturers dare not
publish their full interface specifications, since that would make it
much easier for competitors to figure out whether any patents are
being infringed.  (Of course