Do you use [Potlatch 2](//wiki.openstreetmap.org/wiki/Potlatch_2)? Switch to Advanced Mode (bottom left corner of the editor window) and set the surface. In Simple mode Potlatch 2 interprets the tags and does only offers a limited choice of tag values.

Do you use [Potlatch 2](//wiki.openstreetmap.org/wiki/Potlatch_2)? Switch to Advanced Mode (bottom left corner of the editor window) and set the surface. In Simple mode Potlatch 2 interprets the tags and does only offers a limited choice of tag values.