I have hundreds of lines of code of the form
\Umathcode`a = 0 \symwmb "1D4B6
and
\Umathcode"03B1 = 0 \symrmtl "0000B
where, in the latter case, there is a counterpart \def\alpha{^^^^03b1},within commands of the type in David Carlisle's answer in Greek letters within \mathsf, \mathsfit, \mathbfsf, and \mathbfsfit without using unicode-math that map character codes to characters in various fonts. Since I am reusing the Latin and Greek alphabets in several such commands, it occurs to me that it should be possible to create several globally-defined comma-separated \clists from LaTeX 3 code that is available in xparse (actually, from what I have read, \seqs may be more versatile in this case) and reuse them. So I need to write a command of the form
\MapCodes{LatinLower}{\symYYYY}{1D486, 1D487, 1D488, ... 1D4CF}
that can be called from within each of the \symXXXX commands in like those in David's answer to my previous question that would then execute this sequence of commands within the scope of the calling command. Here, LatinLower is a list or sequence containing the Latin lowercase letters and could be globally defined, \symYYYY is the font declared with DeclareSymbolFont{YYYY}{TU}{<NFSS family>}{m}{n}, and the last argument is the list of slot numbers for the particular font which correspond to the lowercase characters desired.
I am pretty certain this is doable, but I am a newbie to LaTeX 3 and learn most easily by example anyway, so I can either spend all day trying to figure this out from interface3.pdf or just ask and learn from the answers. I hope I have adequately explained what I am trying to accomplish.