Sounds like target in this instance might be referencing a window,iframe or such to place the results in rather than a target outside the page.
Probably there is something IN THE PAGE with an id or name “mainframe”, and if this is a FORM element without an ACTION attribute , then likely the lookup is being done with a javascript function and you would have to copy the related SCRIPT tag , the FORM and it’s children to the page where you want to use it and make sure there was some iframe or something to name “mainframe” for the search results to be dumped in