% page independence in reverse order should not mess it up
\documentclass{article}
\begin{document}

\unitlength 0.001in

No PN (invalid usage for test purpose only)\par
\begin{picture}(850,550)(-50,-500)
  \special{ar 400 250 400 250 0 6.28319}%
  \put(400,-250){\makebox(0,0){document}}%
\end{picture}
\newpage

No PN (invalid usage for test purpose only)\par
\begin{picture}(850,550)(-50,-500)
  \special{ar 400 250 400 250 0 6.28319}%
  \put(400,-250){\makebox(0,0){document}}%
\end{picture}
\newpage

PN 30 (explicit)\par
\begin{picture}(850,550)(-50,-500)
  \special{pn 30}%
  \special{ar 400 250 400 250 0 6.28319}%
  \put(400,-250){\makebox(0,0){document}}%
\end{picture}

\end{document}