Syntax: select None, Classes, Inline or Bold
The user's query will be highlighted in various parts of the search results (Title, Abstract, etc.) with the selected method:
None or N - No highlighting will be done in search
    results.Classes or Y -
    Terms will be highlighted with <span> tags
    that refer to classes that are defined in a separate CSS file,
    /common/search.css by default.  Each term in the
    query is tagged with a different class, which are each highlighted a different
    color in the default search.css.  All these rules can be overridden
    with your own CSS on the results page.Inline - Terms will be highlighted with <span> tags
    that directly specify a fixed CSS style.  This is not customizable,
    but is self-contained and does not depend on a separate stylesheet
    or file.  Same visual result as Classes with the default CSS.Bold - Terms will be highlighted with <b> tags.
The default is Bold.