additional graphical parameters in contour function

Do you know why additional graphical parameters (like "type","pch", ...) 
do not work in the R contour fonction. For example the command 
'contour(..., type="o",pch=16)' gives nothing, just simple contour lines.

Please, can you explain why you think it does make sense here?

The reason is that I want to add on a same graphic several contour plot, and 
I want to give different line types for each contour. I thus thought that 
these options of the contour function made it possible to do it.

Thank.