Between the city of publication and the name of the publisher in literary references.
"The Practice of Typography." New York: Oswald Publishing Company.
The colon has been similarly employed in the imprints on the title pages of books.
New York: Harper & Brothers, 1880.
DeVinne remarks upon this use of the colon that it is traditional and can not be explained.
The colon is sometimes used between the hours and minutes in indicating time, like: 11:42 a.m.
DeVinne does not approve of this, though other authorities give it as the rule.

It is probably better to use the period in spite of its use as a decimal point, which use was probably the motive for seeking something else to use in writing time indications.

In railroad printing the hour is often separated from the minutes by a simple space without any punctuation.
THE PERIOD The period, or full stop, marks the end of a declarative sentence.

As a sign it has several other uses which will appear in the paragraphs following.
_Rules for the Use of the Period_ 1.

At the end of every sentence unless interrogative or exclamatory.
2.