Nath is a LaTeX (both 2e and 2.09) style to separate
presentation and content in mathematical typography. The style
delivers a particular context-dependent presentation on the
basis of a rather coarse context-independent notation.
Highlighted features: depending on the context, the command
\frac produces either built-up or case or solidus fractions,
with parentheses added whenever required for preservation of
the mathematical meaning; delimiters adapt their size to the
material enclosed, rendering \left and \right almost obsolete.