The same rule holds in the case of manuscripts edited before being sent to the composing room.

The editor has assumed all responsibility for the accuracy of the copy.

In a great many cases the copy will come in carelessly written and wholly unedited.
In such cases the compositor should punctuate as he goes along.
This is one of the tasks which subject the compositor to the test of intelligence.

Printing is not now and never will be a purely mechanical trade.

A printing office is no place for an apprentice who can not learn to think.
This book contains a description of the functions of the punctuation marks and the common rules for their use.