LOL...I , ashamed to admit , have never paid any attention as to the type of string.
I buy 300' rolls of masons line. to use when i rough in a building.
i cut off a approx 6' length to cut a pipe and disgard when its cut.
i even have used the string from inside my chaulk box, what ever is handy/available when the need arises
mostly use a saw zall, with a 12'' blade., grinder, or dremel