Parameters & Google Search Appliance
Search Protocol Reference for Google Search Appliance is a good place to start to see all available parameters and what they include.
Additional fields can be added to search forms to retrieve content based on meta-data, collections, date ranges, page titles, sites, and more.
URLParams plug-in for Firefox as an easy way to view and modify parameters after submitting a search.
Use getfields = * to return all meta-data for pages. If you’re going to use meta-data in your search results you must get meta-data using this parameter.
Boolean logic can be used with any parameter or collection. AND (.), OR (|), NOT (-), use parenthesis to direct to evaluate Boolean first.
Interface can be built in GSA using XSLT or can be created in the language of your choice and passing XML results back and forth to GSA. JavaScript and jQuery can also be used in HTML form if you don’t want to use server-side technology.
Enhanced Simple Search
Using operators, but operators may be difficult for users to remember. These can be submitted in the URL string using form fields in search.
Use a simple HTML form to submit data strings on search.
Google Admin Interface
Set where to get dates from your pages using Document Dates (under Crawl and Index).
Collections Versus Meta-data
Collections are vertical. Examples, all PDF’s, all Word files, sub-section(s) of your site, or multiple web sites.
Meta-data is horizontal, across all collections.
Advanced Search
Start out using the advanced search out of the box. By looking at the source of the page, you can see the page is generated using an HTML form.
Google Search Appliance Form Generator was built to help people understand how to put together advanced search interfaces. It generates a form which can be used as a start for your search interface. It also gives you hints for various search parameters.
More info