From: helbig@asclothestro.multivax.de   
      
   In article , Hendrik van Hees   
    writes:   
      
   > These are great journals since they care for century-old good practice   
   > in microtypography.   
   >   
   > The rules are that mathematical constants like i, e, pi etc. are set   
   > upright. The same holds for operators like the differential d. All units   
   > have to be set upright.  Physical constants (even those which are   
   > exactly defined in the new SI like c, h, \hbar, etc.) however have to be   
   > set in italics.   
      
   Right; that seems to be what the journals who care about those things   
   do.   
      
   > The Newton gravitational constant is also to be set in   
   > italics (it's not even a fixed value in the SI for understandable   
   > reasons).   
      
   True, but it is certainly not a variable in the mathematical sense.   
      
   > All variable quantities are set in italics.   
      
   My question is really why mathematical, but not physical, constants   
   should be upright.  In maths is clear: italic means variable, upright   
   means constant or label or operator or unit.  In physics, italic means   
   variable OR constant, upright means label or operator or unit.   
      
   > The only exception are   
   > capital greek letters (in the German and the Anglo-Saxxon tradition; the   
   > French also set these letters in italics).   
      
   What is a common example of a capital Greek letter being used as a   
   variable?  Perhaps the Gamma factor in special relativity?  (Zel'dovich   
   used Delta = 1 - 1/(1+z) for the cosmological redshift, but that has   
   gone out of fashion.)   
      
   > The same holds for indices,   
   > which are variable (e.g., running over 1 to 3 in 3D in Euclidean or from   
   > 0 to 3 in Minkowski/GR vector calculus). In contradistinction to that if   
   > the index is a descriptor like $k_{\text{B}}$, where the B stands for   
   > Boltzmann and is not variable, it should be set upright.   
      
   Right; it is a label.   
      
   > In LaTeX there are extra packages for a full upright Greek math   
   > alphabeth (it's also included in the exceptionally good font package   
   > mathdesign, where you have the choice full math alphabeths in very nice   
   > fonts like Garamond, Utopia, Charter).   
      
   Yes, I've used some of those.  At least in some cases, the upright   
   letters have new commands, since the usual ones are used for the italic   
   characters.  This makes it a pain when recycling something like a   
   complicated formula.  In general, I try to have all differences between   
   journals which are not handled by the corresponding LaTeX class handled   
   by my own macros.  So first I load my own macros, which are my   
   defaults, then journal-specific macro packages which redefine things   
   which differ from my defaults.  (That applies to many things, such as   
   spelling, punctuation, italicization (or not) of foreign expressions,   
   forms of dashes, and so on.  Using \newcommand, \renewcommand, and   
   \providecommand gives the necessary flexibility (e.g. one can define   
   something (sensibly, with the same definition) if it hasn't been defined   
   by the class, otherwise use the definition from the class).   
      
   So basically, my question is what should the defaults be, but it seems   
   that you agree with the great journals, so I'll go that route.   
      
   But what is the origin of the difference between mathematical and   
   physical constants and for the exception to set capital Greek variables   
   upright (but not in France)?   
      
   Of course, $W$ is the variable for energy, W the unit watt, $m$ the   
   variable for mass, m the unit meter, and so on.  Could that be the   
   reason?   
      
   What about alpha, beta, and gamma rays?  Should probably be upright?   
      
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