Prevents Google from showing a Site Links search box.
https://support.google.com/webmasters/answer/79812
Widgets · Site Search
Get access to data on 7,457 websites that are Google No Site Links Search Customers. We know of 4,595 live websites using Google No Site Links Search and an additional 2,862 sites that used Google No Site Links Search historically and 2,016 websites in the United States.
Get a list of 7,457 websites using Google No Site Links Search which includes location information, hosting data, contact details, 4,595 currently live websites and an additional 33,953 domains that redirect to sites in this list. 2,862 sites that used this technology previously and 2,016 websites in the United States currently using Google No Site Links Search.