isindex element informs the browser that the document is an
index document. As well as reading it, the reader may use a
The document can be queried with a keyword search by adding a question mark to the end of the document address, followed by a list of keywords separated by plus signs. See the network address format for more information.
isindextag automatically. If added by hand to an HTML document, the browser assumes that the server can handle a search on the document. Obviously the server must have this capability for it to work: simply adding
<isindex>in the document is not enough to make searches happen if the server does not have a search engine!