# [texhax] Units in technical writing

Thu Dec 29 10:41:56 CET 2011

Reinhard Kotucha wrote, On 2011-12-29 03:22:
> On 2011-12-28 at 16:04:28 -0800, Robert Wilson wrote:
>
>  > I'd like to ask a related question on what is the appropriate way to
>  > typeset units. Italic?
>
> No, units are typeset upright always.  Only variables are typeset
> italic.  Operators like d (differential) or i, j (complex) or e
> (exponential) are typeset upright.  They are not variables.
>
> And text is always upright, even in math formulas:
>
>

I tend to recomment \textup here instead of \mathrm, for several
reasons: (1) Then national chars are allowed, (2) the text font is used,
the 'text index' is a textual property, and thus should be in the text font.

> If you look at the output carefully, you see immediately that the
> latter variant must be wrong (no ligaturtes, awful kerning).
>
>  > Space between number and unit?
>
> Yes, or maybe better a thin space (\, in LaTeX).
>

That might actually depend on that is written. If it is an abbreviation
then thin space is used (as siunitx does), but if the full name of the
unit is written a normal space should be used, i.e.

10\,m  vs. 10~metres

At least that is what I recommend our users (with a heavy emphasis on
using siunix, Joseph did a great job in that one)

>  > I've never been able to find an authoritative style guide.
>
> I'm sure there are ISO standards but I fear that you have to pay for a
> copy.  You'll probably find them in a library of a university.
>
> Another valuable source is TUGboat, http://tug.org/TUGboat .  There
> are often quite interesting articles about math typesetting.
>
> The siunitx (LaTeX) package has all the rules built-in.  It's also
> worthwhile to consult its documentation.  The reference section
>
> And even if you don't read anything at all, there is a simple rule:
> Everything within a math formula has to be unambiguous.  If variables
> are italic, units have to be typeset differently.
>
> Regards,
>   Reinhard
>

--

/daleif