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\setuppagenumbering[location=]
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\def\Head{%
    \NC \tex{unit} argument \NC desired \NC \tex{unit} output \NC\NR \HL}
\def\Unit#1#2{%
    \NC \type{#1} \NC #2 \NC \unit{#1} \NC\NR}

In beta 2011.11.25 Hans has kindly fixed most of the bugs identified in
\tex{unit} and only a few problems remain.

%\registerunit [units] [litre=L]
%\registerunit [units] [metre=m]

Litre and metre are still a problem (but can be fixed using \tex{regiterunit}):

\starttabulate[|lw(0.5\textwidth)|lw(0.2\textwidth)|lw(0.25\textwidth)|]
\Head
\Unit{1 litre / second}		{1 l/s}
\Unit{1 metre / second}		{1 m/s}
\Unit{1 m/s}			{1 m/s}
\Unit{1m/s}			{1 m/s}
\stoptabulate

Temperature symbols should be \quote{℃} and \quote{℉} (Unicode 2103 and 2109;
the latter for Fahrenheit does not seem to print). I note Hans has marked
this as {\em todo} in \type{phys-dim.lua}; hopefully that will fix the
examples below. (Yes, strictly the last two should be
\unit{watt per meter kelvin} but the Celsius unit is equivalent and valid
in this context).

\starttabulate[|lw(0.5\textwidth)|lw(0.2\textwidth)|lw(0.25\textwidth)|]
\Head
\Unit{0 celsius}		{0 °C}
\Unit{32 fahrenheit}		{32 °F}
\Unit{0.123 ohm per celsius}	{0.123 \textohm/°C}
\Unit{5 watt per meter celsius}	{5 W/m\cdot °C}
\Unit{5 watt per meter degree celsius}	{5 W/m\cdot °C}
\stoptabulate

I missed a number of SI units in \type{phys-unit.lua}: I will send Hans a 
full list, but they include radian and steradian, symbols rad and sr.
(\type{phys-unit.lua} does have \quote{sterant} which I believe to be a typo):

\starttabulate[|lw(0.5\textwidth)|lw(0.2\textwidth)|lw(0.25\textwidth)|]
\Head
\Unit{$2\pi$ radian}		{$2\pi$ rad}
\Unit{$4\pi$ steradian}		{$4\pi$ sr}
\Unit{100 lumen}		{100 lm}
\Unit{23 centi stokes}		{23 cSt}
\Unit{0.123 neper}		{0.123 Np}
\stoptabulate

Note also that a leading space has crept in in the radian and steradian
examples, presumably caused by my use of math mode; but radian and steradian
quantities are often expressions involving $\pi$.

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