Mode of Correcting a Proof.
It is interesting to see that the standard proofreader’s marks have
hardly changed at all in two centuries. If you were to follow these rules
in any large publication today, your editorial marks would be instantly
understood, with the possible expression of striking out superfluous
letters, which is now indicated by a simpler loop. Yet these marks come
from a printer’s guide published in 1825.
From The
Printer’s Complete Guide, 1825.