3. A period and a dash are generally used after a side-head. The dash sets the group of words off from what follows, and thus shows at a glance that the words are a heading, and not a part of the sentence following. This style is very common, and is helpful to the reader. Side-heads are generally put in italics, but often in small capitals or bold-face type.
The same marks are put after the word “Note” (the word is generally printed with a capital and small capitals) when used to introduce remarks (a note) in the text.
4. The period and dash are used before the name of the author or the title of the work following a quotation when the name of the author or the work begins on the last line. If such name is dropped below the last line of type, the dash alone is used before the name.
5. The period is used to indicate abbreviations. (See Chapter XIII.)
6. The period is used by some printing-offices, notably The Riverside Press, between the figures expressing the time of day:
91. The train arrives at 6.20 P. M.
As this makes the “20” look like a decimal, the style is not to be commended.
7. The period is used to indicate decimals.
Note.—Quite contrary to the statement made in not a few school text-books, a cipher standing alone frequently precedes the decimal point, and is useful when it will prevent an error that is especially to be guarded against,—for example, in a physician’s prescription. It is easy to read “.1 gm.” as one gram; but “0.1 gm.” is quite unmistakable, even with a faint mark for the decimal sign (period), because the spacing between the figures serves to show that a period belongs there.