Search guide
Find your way through the archive
Start with a title, filename, or a few words from a document.
Combine terms
| Query | Finds |
|---|---|
navy ships | Both terms; a space means AND. |
ships OR weapons | Either term. |
ships AND NOT missiles | Ships, excluding the exact word missiles. |
navy AND (ships OR weapons) | Groups alternatives with parentheses. |
"deep space" | Consecutive words within the same field. |
NOT weapons | All items except those with the exact word weapons. |
Use uppercase AND, OR, and NOT for operators. Evaluation order is NOT, then AND, then OR. Parentheses override that order. Put an operator word in quotes to search for it literally.
Spelling variations
Turn on “Include spelling variations” to accommodate typing errors in included terms. Exclusions and quoted phrases stay exact. Terms of 1–3 characters stay exact; terms of 4–7 characters allow one edit; longer terms allow two. An insertion, deletion, substitution, or adjacent transposition counts as one edit.
Matching and ranking
Matching ignores case and normalizes Unicode. Punctuation separates words. Accents and numbers are retained. There are no automatic synonyms or word stems. Exact matches rank ahead of results needing spelling variations; titles and filenames rank ahead of descriptions and document text.
Coverage and limits
HTML and plain-text contents are indexed where readable. Other formats, preserved directory listings, and files with unresolved legacy encodings have metadata-only coverage. Search does not inspect compressed archives or scanned pages.
Queries allow up to 512 characters, 64 terms or phrases, eight nested groups, and 100 spelling alternatives per term. Exceeding a limit produces an explanation; search never silently discards alternatives.
Use the collection and file-type filters to narrow the complete query. Search requires JavaScript; collection browsing and downloads work without it.