The siunitx manual suggests using \DeclareSIUnit\Molar{\textsc{m}} as the symbol for Molar but this creates a small cap M. This is (apparently) how Molar was defined in version 1 of siunitx. However, L for Liter is upper case, not small cap, which creates (at least to me) typographical conflict. Is there a typographical or other standard I am not aware of for these symbols, or should I simply use an upper case M for Molar?

\DeclareSIUnit\Molar{\textsc{m}} % pg. 39 siunitx manual (2013/03/11)


\si{\Molar} \si{\liter}


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  • 1
    I suppose the use of \textsc{m} for "Molar" is intended, in part, to avoid confusion with M, which is a common abbreviation for "Mega". Since (to the best of my knowledge) there's no similar use of L, there's no danger of confusion arising when one encounters an L in some expression, right?
    – Mico
    Commented Jul 11, 2014 at 19:24
  • 1
    @Mico - You may be right. We would not want to confuse Megameter with Megamolar! :) I just looked at the NIST Guide for the Use of the International System of Units and they use a small cap M for molar solutions (but only to say they are obsolete). They use an italic M for molar mass (kg/mol), which would also potentially cause confusion. Commented Jul 11, 2014 at 19:46
  • 4
    Small caps 'M' for molar is common in chemistry journals, hence the suggestion. On the other hand, small caps 'L' is only ever used for L/D stereochemistry, so for litres (if used), an upper case L is typical. (I'd always use cm3 for volume anyway, as historically there were some issues with litres.)
    – Joseph Wright
    Commented Jul 11, 2014 at 20:51


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