Partly solved: Re: Nomenclature with Sections

[Wolfgang Engelmann]

To get parts of the nomenclature as a separate section,
I have in my preamble

\usepackage{ifthen}
%Creating Nomenclature with Sections
\renewcommand{\nomname}{Glossar}
\renewcommand{\nomgroup}[1]{%
\ifthenelse{\equal{#1}{A}}{\item[\textbf{Roman Symbols}]}{%
\ifthenelse{\equal{#1}{G}}{\item[\textbf{Greek Symbols}]}{%
\ifthenelse{\equal{#1}{C}}{\item[\textbf{Abbreviations}]}{%
\ifthenelse{\equal{#1}{S}}{\item[\textbf{Subscripts}]}{%
\ifthenelse{\equal{#1}{Z}}{\item[\textbf{Mathematical Symbols}]}
{}
}% matches mathematical symbols
}% matches Subscripts
}% matches Abbreviations
}% matches Greek Symbols
}% matches Roman Symbols

using in the nomenclature items
symbol       e.g. 2D
description  e.g. twodimensional
sort as      C

I get at the end of the nomenclature (glossary) after my last normal item
Zeitgeber time (ZT) or time cue, synchronises an oscillation

Abbreviations

2D twodimensional
3D threedimensional
...

At the begin of my nomenclature i get
Roman Symbols
and as the first item
action potential ...

I would like to have the nomenclature start immediately with the first 
item, not with the heading Roman Symbols

and furthermore to have the heading Abbreviations not behind the last 
item, but extra, e.g. as a
subsection Abbreviations

I don't know how to achieve this

Wolfgang