No indent on first paragraph of a section with KOMA script

Question

I am trying to reproduce the behavior described in this question in a scrartcl document class using KOMA script.

My understanding is this is the default behavior for the article document class. However, KOMA script's default setting forces an indent on all paragraphs, including the first paragraph of a new section.

Answer 1

The suppression of the indentation of the paragraph following the heading is the default behaviour of the KOMA-Script classes, too.

Example:

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\begin{document}
\section{Foo}
\Blindtext[2]
\section{Bar}
\Blindtext[2]
\end{document}

scrartcl declares section with the following code:

\DeclareSectionCommand[%
  style=section,%
  level=1,%
  indent=\z@,%
  beforeskip=-3.5ex \@plus -1ex \@minus -.2ex,%
  afterskip=2.3ex \@plus.2ex,%
  tocstyle=section,%
  tocindent=0pt,%
  tocnumwidth=1.5em%
]{section}

Note, afterindent is not set explicitely. So the default afterindent=bysign is active and the negative sign of beforeskip supresses the indentation of the first paragraph following the heading. The vertical skip before the heading is still positive.

If you want to change the value of beforeskip, you have to use the minus sign for its length , eg

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\RedeclareSectionCommand[
  beforeskip=-10ex plus -1ex minus -.2ex
]{section}
\begin{document}
\section{Foo}
\Blindtext[2]
\section{Bar}
\Blindtext[2]
\end{document}

Alternatively you can use a positive value for beforeskip and change afterindent to false:

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\RedeclareSectionCommand[
  beforeskip=10ex plus 1ex minus .2ex,
  afterindent=false
]{section}
\begin{document}
\section{Foo}
\Blindtext[2]
\section{Bar}
\Blindtext[2]
\end{document}

Both results in

---

Warning: If you only change afterindent to true or false without changing beforeskip to a positive value, the section heading could overlap the text before it:

Code:

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\RedeclareSectionCommand[
  afterindent=false
]{section}
\begin{document}
\section{Foo}
\Blindtext[2]
\section{Bar}
\Blindtext[2]
\end{document}

Answer 2

It didn't take me long to find the answer: Setting afterindent=false in \RedeclareSectionCommand does the trick.