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This article is a list of standard proofreader's marks used to indicate and correct problems in a text. Marks come in two varieties, abbreviations and abstract symbols. These are usually handwritten on the paper containing the text. Symbols are interleaved in the text, while abbreviations may be placed in a margin with an arrow pointing to the problematic text. Different languages use different proofreading marks and sometimes publishers have their own in-house proofreading marks.
Depending on local conventions, underscores (underlines) may be used on manuscripts (and historically on typescripts) to indicate the special typefaces to be used:
single dashed underline for stet, 'let it stand', proof-reading mark cancelled.
single straight underline for italic type
single wavy underline for bold type
double straight underline for SMALL CAPS
double underline of one straight line and one wavy line for bold italic
triple underline for FULL CAPITAL LETTERS (used among small caps or to change text already typed as lower case).
The style guide for publications of the European Union is presented in 24 European languages and includes a section on proofreading. Each edition has a sheet of proofreader's marks that appears to be the same apart from the language used to describe the marks. The section cautions that "it should be realised that the typesetter may not understand the language in which the text is written".