21 US and British English
Note that there are some differences in the terminology of marks of punctuation between dialects. The British terms are used in the discussion below, but it is important to be aware of the following differences: the full point is called a period in US English; the exclamation mark may be called an exclamation point; the em rule and en rule are called an em dash and en dash; curly brackets (braces) are sometimes called wavy brackets; the solidus is called a slash. The term inverted commas is not used in US English for quotation marks, and round brackets is not used of parentheses.
See 4.3 for guidance that is pertinent to both dialects. US style is to insert a comma after the phrases for example and that is, whenever they occur and are not followed by stronger punctuation, such as a colon. US style also prefers commas after the common abbreviations of these phrases, e.g. and i.e., even though this results in double punctuation. See 10.6.
US style places commas inside closing quotation marks. See 9.2.3.
As noted at 11.3, US style is to separate the hours and minutes in numerical representations of time with a colon, e.g. 5:23 am. British style often uses a full point: 5.23 am. In US style the first word of a sentence after a colon is often capitalized, but is lower case in British.
21.2.3 Full point
US style places full points inside closing quotation marks. See 9.2.3.
There is some variation within and between the dialects in the use of full points with abbreviations. This subject is covered in 21.4.4.
See 4.11 for the main discussion of UK usage. En rules (dashes) in US usage are used to join open elements into compounds (for example, the post–Civil War armistice), and a hyphen rather than an en rule is used to create a compound derived from two names (Marxist-Leninist theory).
21.2.5 Quotation marks
See 4.14 for the main discussion. Changing the style and placement of quotation marks and their accompanying punctuation for correct localization of text can be a tedious exercise because of the stylistic variations between British and US English.