This is also why I fervently support the Q. It is based on SI, the mm, even
though it is a quarter of that unit, still simply expressed with the decimal
fraction 0.25. And it replaces a lot of garbage. But it should never become
an SI unit; rather see it as an industry standard or module.

Another thing: there are now three US cosmetics companies which use the
Franco-US unit once liquide on their labels. It seems to be spreading! We
had Estee Lauder, the inventors of this travesty, then Donna Karan. Now they
have been joined by Tommy. When 2010 looms and the TABD starts its game
afresh, I will use this as evidence of abuse of the EU tolerance in my
petition to the European institutions.

Han


----- Original Message -----
From: "Jim Elwell" <[EMAIL PROTECTED]>
To: "U.S. Metric Association" <[EMAIL PROTECTED]>
Sent: Friday, 2002-03-15 20:21
Subject: [USMA:18773] Short unit names


> Engineers who work with human-readable displays are familiar with the unit
"nit", which is one candela per square meter (cd/m^2). It is used to specify
how bright a display is (either directly for some types, or via backlighting
for others). For example, a 150-nit display will be readable in roomlight,
but washed out in sunlight, whereas a 600-nit display will be
readable in sunlight, but too bright for viewing in a darkened room.

 The unit "nit" is used for two reasons: displays are a distributed light
source rather than a point source (so lux is not appropriate), and, used
properly, it is a photonic unit, which means it takes into account the
 response of the human eye.

 There clearly is no directly equivalent SI unit here, due to the photonic
nature. But I think engineers use it for another reason: it is a short, one
syllable word. It is a heck of a lot easier than saying "photonic-weighted
candela per square meter."

 I bring this all up to make two points: (a) SI does *not* cover all
necessary uses of measurement systems, so there are going to be new units
"invented," although we hope they are based on SI (as nit is) and (b) people
inherently like short words, which I think is one thing that turns people
off about the metric system (e.g., inch vs. centimeter).

 I doubt anything can be done about (b), but I bet that words like "klick"
(for kilometer) are not going to be eradicated even in all-metric countries.

 Jim Elwell




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