Some of the options in the Type details drop-down menu are:

Plain

Choose this option if your media stock does not require a special description. Some systems require a value of plain, but leaving this blank if the detail is not needed would be better, if the print engine allows it.

Cardboard

Media made from cardboard stock.

Continuous Long

Opaque media composed of sheets continuously connected along the long edge, as defined by Size.

Continuous Short

Opaque media composed of sheets continuously connected along the short edge, as defined by Size.

Labels

Adhesive label stock, such as a sheet of peel-off labels.