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abbreviations and acronyms

An abbreviation is a shortened form of a word used in place of the full word (e.g., Inc.). An acronym is a word formed from the first letters of each of the words in a phrase or name (e.g., NREL or DOE). Abbreviations and acronyms are treated similarly in NREL publications. 

  1. Using Abbreviations and Acronyms Sparingly
    Avoid using a given acronym unless you use it extensively in a publication. In a short report, do not use an acronym for a phrase you use five or fewer times. In a long report, do not use an acronym for a phrase you use fewer than 10 times. In a webpage, do not use an acronym for a phrase you use fewer than three times.

    Some two-letter abbreviations and acronyms are acceptable (e.g., AC and DC, or MW). Avoid other two-letter acronyms that are less universally used (e.g., EE and RE).

    If you use many acronyms in a report, add a list of acronyms at the beginning of the report. For an example, see this sample report.

  2. Spelling out Acronyms
    In general, each time you use an acronym for the first time in the body of a report or on a given webpage, spell it out and put the acronym in parentheses after the full name. However, you do not need to spell out most common abbreviations and acronyms (e.g., AC, DC, cm, m, Hz, kW, MW, GW, and rpm) in most technical reports.

  3. Abbreviating Measurement Units
    Spell out a technical abbreviation in full in text when you use it without numerals. For example, write "a few centimeters" rather than "a few cm."

    Abbreviate units of measurement when they are used with a numeral or numeric value (e.g., 900 W/m2, 43 cm, or 60 Hz). With a few exceptions (such as %, °, $, and ¢), use a space to separate them from numerals.

  4. Abbreviating Plurals
    Use a small s (no apostrophe) for plurals of most abbreviations. For plurals of units of measurement, omit the s (e.g., 15 cm, 6 m, 5 million Btu, 75 dB, 40 W).

  5. Abbreviating Equations and References
    You can abbreviate "equation" and "reference" when you use them with numbers, but spell them out at the beginning of a sentence.

    See Eq. 1-1, Eq. 2-7, and Ref. 10.
    Equation 2-1 shows the relation.
  6. Abbreviating in Journals
    For a journal article, consult the publisher's or professional society's guidelines for abbreviations, if they are available. For abbreviations of journal titles, please see the Woodward Library website.
Subjects:  Data and MeasurementWriting Style

bio

Follow the general rule for prefixes and do not use a hyphen:

biocrude
bioblendstock
bioeconomy
bioproduct

Exceptions include “bio-based,” “bio-derived,” and “bio-oil.”

Subject:  Technology-Related Terms

capitalization

1. Proper Nouns

Capitalize proper names. These include the names of government programs, official projects, formal groups, organizations, companies, titles when they precede a name (use lowercase in titles that follow the name), specific geographic areas or features, and ethnic groups.

When referring to NREL, "National Renewable Energy Laboratory" is capitalized, but "the lab," "the laboratory," and "national laboratories" are not.

the Alcohol Fuels Program
the Ethanol Project
the Human Resources Office
the U.S. Bureau of Mines
Solarex Corp.
President Carter
Christine Johnson, president and chief executive officer
the Southwest
Lake Powell
the Colorado River
African, Asian, Black, Caucasian, Hispanic, or Native Americans

One exception to this rule is companies and products with stylized lowercase or "camel cap" names (e.g., eBay, iPhone). In these cases, use the company’s or product’s preferred capitalization.

2. Figure Captions, Table Titles, and Section Headings

Figure captions: Capitalize only the first word and proper nouns in figure captions. No period needed (unless there are multiple full sentences).

Figure 1. Results for the electrochromic window developed at NREL

Table titles and section headings: Capitalize the main words of table titles and headings and subheadings, including the second word in a hyphenated term (e.g., "PV Program Five-Year Plan"). No period needed.

Table 1. Number and Frequency of Defects in Six Samples

Testing the 7.6-m Blades
Results for E. Coli
Development of Method To Detect Anomalies

Do not capitalize:

  • Articles (e.g., "a," "an," and "the") unless they begin the title or heading
  • Conjunctions of three or fewer letters (e.g., "and," "or," "nor," "yet," "so," and "but")
  • Prepositions of three or fewer letters (e.g., "for," "of," "on," and "up").

Do capitalize:

  • Conjunctions (e.g., "than") and prepositions of four or more letters (e.g., “from,” “with,” “above,” “after,” “down,” “inside,” “over,” and “into”)
  • "To" as an infinitive (but lowercase as a preposition, e.g., “Scientists Travel to Chile To Engage Utilities”)
  • Verbs, including "is" and "are."

For journal/conference submissions or other non-NREL publications, follow the style recommended by the professional society or publisher.

3. Titles

Capitalize titles when they precede the person's name. Lowercase titles and names of groups when they follow the name.

Chief Operating Officer Mark Wilson
Mary Jones, the president of the company
John Smith, the chair of the committee

4. Trade Names

Capitalize trade or brand names, and include a trademark, copyright, or other symbol only when it's an Alliance-registered trademark. Include the symbol the first time you use the trade name in body text (not in a title, acronym list, or section header); thereafter, you may omit the symbol. Also use superscript for trademark symbols. See the trademark symbols entry for a list of Alliance trademarks.

5. Taxonomic Names

When writing about botanical and zoological divisions, capitalize the names of all divisions higher than species: genera, families, orders, classes, and phyla. Italicize genera, species, and varieties.

Clostridium thermocellum
Escherichia coli

After you first mention them (and spell them out), you can abbreviate most generic names followed by species names.

C. thermocellum
E. coli

See also captions, fiscal year, geographic regions, headings and subheadings, states and countries, and tables.

Subjects:  Grammar and UsageWriting Style

cleantech

"Cleantech" is spelled as one word. It is not hyphenated, and the "t" is not capitalized. The word "cleantech" is typically used in reference to investments in sustainable technologies, including renewable energy and energy efficiency. Don't use as a shortened form of "clean technology" in other references.

Subject:  Technology-Related Terms

close-spaced sublimation

The term is "close-spaced sublimation," not "closed-space sublimation."

Subject:  Technology-Related Terms

concentrating solar power

Concentrating solar power (CSP) captures the sun’s heat and uses the thermal energy to produce electricity (e.g., via a steam turbine).
Subject:  Technology-Related Terms

Congress and congressional

Capitalize "U.S. Congress" and "Congress" when referring to the U.S. Senate and House of Representatives. Lowercase "congressional" unless it is part of a proper name.

The U.S. Congress is reviewing congressional salaries. A full list is available in the Congressional Record.

Subject:  Government Terms

dashes

Use dashes (often called "long dashes" or "em dashes") to enclose and set off parenthetical (nonessential but often illustrative) information in a sentence. Also use dashes to set off a list of items separated by commas. Do not add spaces around the dash.

The polymer components of the cell walls—cellulose, hemicellulose, and lignin—provide the feedstocks for these chemicals.

Use an em dash to signal that an important point is going to be made or that a change in the construction of the sentence follows.

The presentation concluded with a discussion of the two project factors that concern contractors the most—cost and time.

The major omission in the project assessment was the delay caused by the circuit failures—everyone knew about it, but no one mentioned it to the reviewers.

You can usually use commas, colons, and semicolons in place of dashes, but dashes add special emphasis.

Use shorter dashes known as "en dashes" (rather than a hyphen or em dash) to indicate a range or to substitute for the word "to."

25–45 cm2
2–5 runs per hour
See sections 3.1–3.6
Jan. 16–Feb. 3, 2011

In date spans, do not use "from" in conjunction with an en dash (e.g., "from Jan. 16–Feb. 3"). The correct form is "from Jan. 16 to Feb. 3" or "Jan. 16–Feb. 3."

Do not use an en dash (or hyphen) to mean "and"; the word "between" is followed by the word "and" (not "to"): between 25 and 30.

Subject:  Punctuation

decision maker

Subject:  Writing Style

dish/engine systems

Use a slash rather than a hyphen.

Subject:  Technology-Related Terms

eco

The prefix “eco-” typically includes a hyphen:

eco-conscious
eco-friendly
eco-routing

Exceptions include “ecotourism,” “ecosystem,” and “ecology.”

Subject:  Technology-Related Terms

energy efficient

Hyphenate “energy efficient” only when used as a modifier:

NREL supports the development of energy-efficient technologies.

The window replacement helped her home become more energy efficient.
Never hyphenate “energy efficiency.”

Energy efficiency strategies in buildings include insulation, daylighting, and plug load management.

Subject:  Punctuation

fonts

Use Times New Roman for the text of NREL technical papers and reports. Use Arial for figures, tables, and headings.

Subject:  Publication Formatting

foreword

The foreword to a book or formal report contains introductory remarks written, and usually signed, by someone other than the author or authors. Brief introductory remarks written by authors are contained in a preface.

Subject:  Publication Formatting

Inc. and LLC

Official company names can use the abbreviation “Inc.” or the initialism “LLC” without first defining these terms. Do not use commas around either term. 

Alliance for Sustainable Energy LLC
Apple Inc.
Subject:  Writing Style

logos

Please see our logo page for proper use of the NREL logo and guidance on NREL branding.

quotation marks

Use quotation marks for direct quotes and the titles of articles, papers, and book chapters. In print, use "curly" or "fancy" quotation marks; on the web, use "straight" quotation marks. 

"Let's meet again in 6 months," the chairman said, "to discuss our progress."
She presented a paper titled "Materials Research in Silvered Polymer Reflectors."

Place commas (and periods) inside quotation marks; place semicolons, question marks, dashes, and exclamation points outside quotation marks unless they're part of the quotation.

"The results are in," he said.
"Can you hear me?" she asked.
Did he really say "I don't believe you"?

Use single quotation marks to indicate a quotation within material that is already enclosed in double quotation marks.

"Explain what you mean by 'confidence,'" she said.

When quotations are longer than two or three lines of text, begin them on the next line and indent them on each side (block quotations). You do not need quotation marks around block quotations, and you can use standard double quotation marks for quotes within block quotations. In in-text quotations, place reference numbers, superscripts, and author-date citations outside quotation marks (but before the final punctuation of a sentence). Place them after the final punctuation of the last sentence in a block quotation.

Subject:  Punctuation

roadmap

“Roadmap” should be used as one word when referring to a plan or document laying out progress or steps toward a goal. “Road map” should be two words when referring to a tool used to navigate or travel via roadways, such as by vehicle. 

Subject:  Technology-Related Terms

table of contents

A table of contents is required in most technical reports. In NREL reports, the table of contents follows the rest of the front matter. Lists of figures and tables follow the contents page(s). Each main section of the report is listed in the table of contents with the page it begins on; some authors also like to list subsections. Nothing that comes before the table of contents (front matter) is listed, but references, bibliography, and appendices (back matter) are listed. Publications for general audiences probably should include a contents list if the publication is more than 10 pages long.

Subject:  Publication Formatting

watt

Subject:  Data and Measurement

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Last Updated Dec. 9, 2024