An auto-completion display type which invokes a
JavaScript callback which is expected to return
HTML, which is then used as the display.
Note that the HTML is not sanitised by Funnelback
so this should only be used for trusted sources.
An example value might be `fetchStockPrice('some-suggestion-specific-code')`
in the context of a results page which defines the following function...
function fetchStockPrice(symbol) {
// Fetch stock market data
var data = remoteServiceCall(symbol);
...
return data.companyName + ' (' + symbol + ') $' + data.currentPrice + ' (Higher: ' + data.hiPrice + ')';
}