If you don't have a good reason to capitalize, don't. Given a choice, use lowercase. Do not capitalize solely for emphasis.
Watch out for phony proper names; terms like naval base and bioassay should not be capitalized.
Although format for headings may vary for special cases, NRaD's present format uses all caps for first- and second-order headings in a document. Third- and fourth-order headings in NRaD documents are set in initial caps.
2. Articles, Prepositions, and Conjunctions
Unless used as the first word, do not use initial caps for the following words in document titles, third- and fourth-order heads, formal titles of people, facilities, or programs.
NOTE: Prepositions of five or more letters (e.g., between, through, within) are usually capitalized in titles.
3. Text References to Figures, Tables, and References
Except at the beginning of a sentence, do not use an initial cap for figure, table, and reference in text.
4. Figure Captions and Table Titles
Use sentence style for figure captions and table titles. Capitalize the initial letter of figure or table and the initial letter of the first word of the caption or title. All other words are lowercased unless normally capitalized.
5. Navy and Government Usage
Use an initial cap for Navy when it refers to the U.S. Navy.
Do not use an initial cap for navy when it is standing alone or used collectively.
Use an initial cap for Fleet when it means the United States Fleet.
Use an initial cap for government only if used as part of a proper name or as a proper name.
6. Organizational Units
Use initial caps for formal names of departments, divisions, and branches.
Use initial caps for formal titles of persons.
7. Names of Facilities
Use initial caps for formal names of facilities.
8. Names of Programs and Projects
Use initial caps for formal names of unique programs and projects.
9. Names of Weapons
Use initial caps for the full or officially abbreviated names of weapons, including parts of weapons or proposed weapons. Do not capitalize the unofficial form.
Use initial caps for the trade names but not for the common nouns that follow, unless they are part of the trade name itself.
11. Computer Terms
For hardware, use names assigned by manufacturers.
Use all caps for programming languages formed as an acronym.
12. Scientific Names of Genera
When a Latin name is given for plants and animals, the genus name has an initial cap; the species name is lowercased.