The term 'PROOFREADER's Instruction' refers to two specific instructions that a PROOFREADER may use when editing a document. The first instruction is 'DELE', which stands for 'DELETE'. This instruction tells the PROOFREADER to DELETE a certain part of the text. The second instruction is 'STET', which stands for 'let it stand'. This instruction tells the PROOFREADER to leave a certain part of the text as it is. Together, these two instructions help the PROOFREADER to make sure that the document is free of errors and ready for publication.