How to let Google detect a site search engine?

Question

Google Chrome has a feature where you can hit tab to search a site. Chrome then navigates to the site's own search engine and runs the inputted query. The Chrome documentation indicates that this is only available if Google has detected a search engine on the site you are trying to search.

This indeed seams to be the case, because writing stackoverflow.com<Tab>test<Enter> makes Chrome navigate here while facebook.com<Tab>test<Enter> does nothing because the tab-key tabbes out of the address line.

What I'm wondering is then how to indicate to Google that my site has a search engine and how Google needs to format a query in order to redirect a Chrome user correctly to my site when the tab-search feature is utilised. Is it a Meta tag? Is it in robots.txt?

Answer 1

After a little digging I found this page that describes this. Also you can read in Stackoverflow's source code and find this line of code:

<link rel="search" type="application/opensearchdescription+xml" title="Stack Overflow" href="/opensearch.xml"> 

What it does is indicate to Google that the description for how to use your search engine in the file /opensearch.xml which contains this:

<?xml version="1.0" encoding="UTF-8" ?> <OpenSearchDescription xmlns="http://a9.com/-/spec/opensearch/1.1/" xmlns:moz="http://www.mozilla.org/2006/browser/search/">   <ShortName>Stack Overflow</ShortName>   <Description>Search Stack Overflow: Q&amp;A for professional and enthusiast programmers</Description>   <InputEncoding>UTF-8</InputEncoding>   <Image width="16" height="16" type="image/x-icon">http://sstatic.net/stackoverflow/img/favicon.ico</Image>   <Url type="text/html" method="get" template="http://stackoverflow.com/search?q={searchTerms}"></Url> </OpenSearchDescription>