I would like to be able to manually redefine quotation mark usage, preferably without having to load an external package.
Judging by the answer to How does TeX's mechanism for sorting out quotation marks work?, it seems that TeX and LaTeX use fonts that feature built-in ligatures to handle quotation mark conversion, while XeTeX and XeLaTeX refer to a map file that has the same function. The quotation marks are effectively ligatures, and not directly defined by the typesetting system.
However, I would like to be able to directly define the expected quotation mark result.
For example, I would like to define commands similar to the following (which do not work):
\def```{\char"201C\char"202F\char"2018\relax}
which should render as something like “‘
.
\def'''{\char"2019\char"202F\char"201D\relax}
which should render as something like ’”
.
I would prefer a solution that could use any character or set of characters as the replacement, because I may have to customize the usage further in the future.