| Name | Purpose | Key | Value |
|---|---|---|---|
| Dictionary | Lookup word meaning | word | meaning |
| Book Index | Find page(s) in a book where a word occurs | word | List of page numbers |
| File Index | Find list of files that contain a given string | string | List of file names |
| Compiler | lookup name usage | program element names (variables, function names, class names, etc.) | Lookup the usage of the name and its attributes |