The extension ".plt" doesn't tell anything. It is an extension that is used by a couple of CAD programs, a.o. AutoCAD and Arkey to identify output files that are intended to be sent to a plotter - these files are usually called "plot files". As the extension ".plt" is given to any plot file from any driver by these programs, the only meaning is that it is some sort of plot file for some sort of plotter. To know what you can do with a given plt file, you should always know where it comes from and what it was made for.
Thank ansi for this details, I now about these. you can make me some suggestion what free software I can use? now I use Corel but is too expansive for what I need. (I have a cut machine)
free software.. not sure there is any... not from what i have searched for anyways. maybe pick up an older vesion of autocad on ebay or something? http://search.ebay.com/autocad_W0QQfrppZ50QQfsopZ1QQmaxrecordsreturnedZ300
http://www.gimp.org not sure if this is really useful, I was doing the same search for free CAD software a few years back if I have time I will have a search on my backups for the software I found
I know many graphic designers that do not want to spend money on software use a program called gimp. Check it out. Thanks. Tom Swanson http://www.xangular.com