Grouping Nomenclature in Latex

See the other post about nomenclature for general usage

the \nomenclature command has some other options given by

\nomenclature[]{}{}

the is replaced by a letter or number to define groups in the nomenclature. You can create group titles by following the 'subgroups' section. If you JUST want to group things together, just use numbers like

\nomenclature[1]{$A$}{The nozzle cross-sectional area}

\nomenclature[1]{$A^*$}{The throat area}

\nomenclature[2]{$\varepsilon$}{The area ratio, $\varepsilon=A^*/A$}

\nomenclature[1]{$M$}{The Mach number}

\nomenclature[2]{$\gamma$}{The ratio of specific heats}

to group the roman and greek letters seperately.

For the aiaa-tc class from aiaa.org i had to do this because they had subgroups defined in the class. There subgroups are

b = subscript
c = convention
g = Symbols
t = superscript

This is usually dependent on \usepackage[]{nomencl} or \usepackage[noprefix]{nomencl} and i haven't messed around too much with other classes, but the aiaa-tc class overwrote the option anyway so i had to use numbers instead of letters for everything.