The Grid Blank command was renamed in Surfer 15; it is now called Assign NoData. This command is available from the Grids ribbon bar tab, in the Edit section:
For more information on using this command in Surfer 15, see:
- Surfer Converting Areas in a Grid File to NoData Training Video
- Can I fill outside a polygon to mask the map outside a boundary in Surfer?
- How can I grid only the area inside my data limits using Surfer?
Updated October 23, 2018