How should supplementary sheets of paper be secured?

Candidates should assemble any loose sheets (including rough work) in the order in which they attempted the questions and to fasten these and any supplementary answer sheets to the back of their answer scripts, or as otherwise instructed, with the string or tags provided by the school (they must not use paper-clips or staples).

It is important that any bar codes on question papers are not obscured when attaching supplementary answer sheets.