begin{pspicture}

psgrid[gridcolor=gray,subgridcolor=lightgray](0,0)(5,5)

rput[bl](0,1){bottom left (0,1)}

rput[tr](5,1){top right (5,1)}

rput[t](2,2){stuff1}

end{pspicture}

I think it :

The optional argument for rput[<refpoint>](x,y){<stuff>} provides the reference point (or anchor) for <stuff>. So, using rput[tl](x,y){<stuff>} puts the top left corner of <stuff> at (x,y). Similarly for rput[bl] and rput[t] (and any of the possible combinations listed in the pstricks documentation.

documentclass{article}

usepackage{pstricks}

begin{document}



begin{pspicture}[showgrid,framesep=0pt](6,3)

psdots(0,1)(5,1)(2,2)

rput[bl](0,1){psframebox{bottom left (0,1)}}

rput[tr](5,1){psframebox{top right (5,1)}}

rput[t](2,2){psframebox{stuff1}}

end{pspicture}



bigskip

begin{pspicture}[showgrid,framesep=0pt](6,3)

psdots(0,1)(5,1)(2,2)

uput{0}[45](0,1){psframebox{bottom left (0,1)}}

uput{0}[-135](5,1){psframebox{top right (5,1)}}

uput{0}[-90](2,2){psframebox{stuff1}}

end{pspicture}



end{document}

In the following example we need 'rput` to put stuff centered to a point:

begin{pspicture}[showgrid,framesep=0pt](5,5)

psdots(2.5,2.5)

multido{iA=0+10}{36}{uput{10mm}[iA](2.5,2.5){psframebox{some text}}}

rput(2.5,2.5){Center}

end{pspicture}

Warning!

The refpoint optional argument only works for "boxed" objects as follows.

documentclass[pstricks,border=1cm]{standalone}



defunboxedObject{psframe(2,1)}

defboxedObject{psframebox{Huge "Age}}



begin{document}    

foreach i in{t,tl,l,bl,b,br,r,tr,t,Bl,B,Br}{%

begin{pspicture}[showgrid,dimen=m](4,3)

    rput[b](2,0.1){bf i} 

    rput[i](2,2){boxedObject}

    %rput[i](2,2){unboxedObject}

    pscircle*[linecolor=red](2,2){2pt}

end{pspicture}}

end{document}

For "unboxed" objects, the argument refpoint does not affect. The terminologies "boxed" and "unboxed" used here have nothing to do with the same terms used in C# or Java programming languages.