How do I know if a rail is sponsered by Eurail as opposed to a local rail? I want to purchase a eurail pass for 5 countries and 8 days of travel, but I don't want to accidentaly use use my days prematurely.
First, Eurail is not a railroad. It is a company set up by a consortium of European national railroads to create and market rail passes for sale to people from outside of Europe. It is accepted by most "local" railroads.
Second, you use a day of the railpass by putting the date on the pass and using it as a ticket. You show the pass to the conductor, and he stamps it to show it has been used. How would you do that accidently? If you don't want to use a day of your railpass, just buy a ticket, like anyone else, and leave the pass in your moneybelt.