mjhjmtu

In math mode, characters and numbers are placed on the baseline and develop upward and/or downward. How can they be centered vertically around the formula axis, as symbols such as + and = are?

For example in:

documentclassarticle
begindocument
$n=0 d(C,P)$
enddocument

The n should be shifted upward, the 0, the d, the C, the comma and the P should instead be shifted downward. How can this be done automatically without having to manually set a raisebox value for each character and/or number?

Thank you for your help, it is very appreciated.

Edit:
I excuse for being unclear about what I want. To clarify, my goal is to achieve what's displayed in the image that egreg posted in his comment. I hope it is clearer now, thank you again.

The following screenshots show first what you say you want -- all letters, numerals, and commas centered vertically on the math axis -- and second what the normal typesetting approach produces, i.e., letters, numerals, and commas all placed on the baseline.

I very much hope that you will agree that the normal typesetting approach is to be preferred. Speaking for myself, centering commas vertically on the math axis borders on the preposterous...

documentclassarticle

usepackage[margin=0pt, paperwidth=3cm, paperheight=0.5cm]geometry
usepackagexcolor,graphicx
usepackage[utf8]inputenc
usepackage[T1]fontenc

% Command to center argument on math axis:
newcommandvc[1]vcenterhbox$#1$ 

%% See https://tex.stackexchange.com/a/414613/5001 for source of the following code
%% Draw a line per font metric (#1 color, #2 vertical position, #3 label)
newcommanddrawmetric[3]rlap%
 color#1rule[#2]2.55cm0.05pt%
 raisebox#2scalebox0.3%
 tinyselectfontsffamily #3%
 
newcommanddrawallmetrics%
 drawmetricred0ptbaseline%
 drawmetricblue1exx-height%
 drawmetricredfontcharhtfont`Xcap-height%
 drawmetriccyanthefontdimen22textfont2math axis

begindocument

noindentrlap % 
 $vcn=vc0 vcc(vcCmathpunctvc,vcumathpunctvc,vcP)$
 drawallmetrics

noindentrlap % 
 $n=0 c(C,u,P)$
 drawallmetrics
enddocument