LaTeX.org

Resolved. Picked up some tidbits from an online latex guide .

Part and chapter have to defined using secdef. The following code illustrates a solution.

\documentclass{article}

\makeatletter
\newcommand\chapter{
\secdef\@chapter\@schapter
}
\def\@chapter[#1]#2{
\normalsize \bf #2 ...

I tried some additional scenarios as follows

\documentclass{article}

\setcounter{secnumdepth}{-2}

\makeatletter
\newcommand\chapter{\@startsection{chapter}{3}{\z@}%
{3.25ex\@plus 1ex \@minus .2ex}%
{1.5ex \@plus .2ex}%
{\normalfont\large\bfseries}}

\renewcommand\section{\@startsection ...

I have experienced the same behavior with the following code:

\documentclass{article}

\newcounter{chapter}
\makeatletter
\newcommand\chapter{\@startsection{chapter}{3}{\z@}%
{3.25ex\@plus 1ex \@minus .2ex}%
{1.5ex \@plus .2ex}%
{\normalfont\large\bfseries}}
\makeatother

\begin{document ...