I'm working on a part of the site that performs a search to a database outside our EPiServer site and I've got a problem redirecting to the "SearchPage". I'd like to use the method used in the template package where this code is used to get the URL to the search page:

        public string SearchPageUrl
        {
            get
            {
                if (_searchPageUrl == null)
                {
                    PageReference searchPageRef = CurrentPage["SearchPage"] as PageReference;
                    if (searchPageRef != null)
                    {
                        PageData searchPage = GetPage(searchPageRef);
                        _searchPageUrl = searchPage.LinkURL;
                    }
                }
                return _searchPageUrl;
            }
            set { _searchPageUrl = value; }
        }

It's CurrentPage["SearchPage"] that gets me confused. I'd like to make another page a sort of search page so that I could redirect to CurrentPage["MyCustomSearchPage"] but I can't figure out where this is done. Where is it declared wich page is the SearchPage?

Best regards