% \begin{macro}{\keyval_parse:n}
% The parsing function first deals with the category codes for
% |=| and |,|, so that there are no odd events. The input is then
% handed off to the element by element system.
% \begin{macrocode}
\group_begin:
\char_set_catcode_active:n { `\= }
\char_set_catcode_active:n { `\, }
\char_set_lccode:nn { `\8 } { `\= }
\char_set_lccode:nn { `\9 } { `\, }
\tl_to_lowercase:n
{
\group_end:
\cs_new_protected:Npn \keyval_parse:n #1
{
\group_begin: