D. For More Desirable Advanced Search Features
A grid-based search engine can provide either the advanced search functionality of the local source or the large-scale free-text searching offered by a web search engine, depending on
what is required. If the user is just interested in one category of data source such as libraries, then they can search that source using the appropriate advanced search features. If, on the other hand, they want to search many different types of sources with incompatible metadata or no metadata at all, then a grid-based search engine will allow them to do a full-text search which would be closer to that provided by the traditional search engine. By using the metadata and search capability inherent in the individual sources, a grid-based search engine will always provide the user with the most advanced search possibilities possible given the sources they choose to search.