"appends" 
 <code>fq</code> params in the configuration of a <a href="../../../../org/apache/solr/handler/component/SearchHandler.html" title="class in org.apache.solr.handler.component"><code>SearchHandler</code></a>, to 
 provide a fixed set of filter options for clients using custom parameter 
 names. 
 Using the example configuration below, clients can optionally specify the 
 custom parameters <code>in_stock</code> and <code>shipping</code> to 
 override the default filtering behavior, but are limited 