# Divide PSTricks script into external files [duplicate]

I have a PSTricks picture shown here, where I have tried to move a part of it into a different ´TeX´-file for clarity (not, this is not a MWE)

\documentclass[pstricks,border=12pt]{standalone}% set border=0pt at the final stage
\usepackage{pst-node}
\psset
{
dimen=middle,
offset=.2,
arrows=|*-|*,
unit=2cm,% set it to 100cm if you want 1 scale = 100cm = 1m
}

\begin{document}
\begin{pspicture}[showgrid=false](5,1.25)% set showgrid=false at the final stage

\include{ext}
\end{pspicture}
\end{document}


with ext.tex

\psframe(1,1)
\psframe(1,.25)(4,.75)
\pscircle(4.5,.5){.5}


Why am I not allowed to do this?