Decimal Notation

The Correct Use Of Em dash —

An em is a unit of measurement defined as the point size of the font — 12 point type uses a 12 point em.

The em dash is used both to enclose and to separate.

Like the comma, an enclosing dash needs a partner.
Enclosing dashes are replacements for enclosing commas in order to add emphasis.

The Em dash — is used—

1. To indicate a sudden break in thought:

   I was thinking about writing a—what time is it?

   If used sparingly it suggests a definite tone, often a note of surprise or an emphasis equivalent to a mild exclamation.

2. To indicate an open range:

   Alan Wood [1951—] authored this document.

   Such as from a given date with no end yet.

3. Two adjacent em dashes are used to indicate missing letters in a word.

   I just don't f— —ing care about 3.0 browsers.

4. To indicate a parenthetical statement that deserves more attention than parentheses indicate.
5. To indicate vague dates.
6. As a stand-in for the last two digits of a four-digit year.

   20—

7. Three adjacent em dashes are used to substitute for the author's name when a repeated series of works are presented in a bibliography. :
8. Three adjacent em dashes are used to indicate an entire missing word in the text.

   An entire missing word in the —

9. Instead of a colon or semicolon—

   Lorem—ipsum

   Used to link clauses

If used regularly in place of commas, colons, and semicolons, it loses all its distinctiveness and becomes a sloppy substitute for conventional punctuation.

The Correct Use Of En dash–

An en is one-half of an em. The en dash is used to indicate a range of just about anything with numbers, including dates, inclusive or continuing numbers, game scores, and pages in any sort of document.

1. pp. 233–235

2. October 1975–January 1976

3. between 1975-1978

It is also used instead of the word to or a hyphen to indicate a connection between things, including geographic references (like the Mason–Dixon Line) and routes (such as the New York–Boston commuter train).

It is used to hyphenate compounds of compounds, where at least one pair is already hyphenated, as in:

• Firefox is an Open–Source–based browser.

Some authors prefer an en dash to a hyphen when text is set in all capital letters.

• THE BOSE–EINSTEIN PAPER

Others specify the use of an en dash when referring to joint authors, as in:

• The Bose–Einstein Paper

Using The Horizontal Ellipsis

An ellipsis … is most often used to indicate one or more missing words in a quotation.

It is also used to indicate when a thought or quotation trails off.

When it occurs at the end of a sentence, it should be treated in one of three ways, depending on usage:

1. If the ellipsis is indicating missing words, then it is followed by a period:
   One or more missing words in the ….
2. If it indicates missing sentences, then it should appear after the period of the preceding sentence, and with a space   on either side:
   An ellipsis is used to indicate one or more missing sentences. … 
3. If it indicates that the thought or quote is just trailing off at the end of a sentence, then only the ellipsis is used, to clarify that no words from a quotation were omitted, as would be the case if the additional period were there:
   An ellipsis is used to indicate one or more missing…